Calculus II Professor will not accept my correct integral evaluation that uses a different method, should I...

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Calculus II Professor will not accept my correct integral evaluation that uses a different method, should I bring this up further?


Are there two answers to this integral problem?Help with understanding the solution to a volume of a solid $y = x, y = 0, x = 4, x = 7$ about $x = 1$Evaluate the Line IntegralRelated Rates- Expanding CircleEvaluating area using an integral in polar coordinatesWithout solving directly for the integral, decide if the value of the integral is positve or negative.Contour integral of $int_gamma frac{z}{sin z}dz$Evaluating integral $iint_{D} 2x-y ,dA$ bounded by circle of a given radiusArea of a square equivelent to that of a circle utilizing caclulusFinding the volume of a solid s using cross sections













3












$begingroup$


I am a freshman enrolled at an American University. Recently, I took an examination in which the following problem appeared:



Evaluate the following integral:



$int_0^4sqrt{16-x^2}dx$



My answer: 4$pi$, was correct. However, I received reduced credit for this answer because I did not solve it correctly (according to the professor). The exams are time-limited and have a fair amount of content, so when I saw this problem, I noticed it was the equation of the top half of a circle centered at (0, 0) and with radius 4. Knowing this, and my knowledge of the integral indicating the signed area under a curve, I merely took the area of a quarter-circle of radius 4, $frac{1}{4}$$pi$$r^2$ and wrote my answer of 4$pi$.



The context of the test was surrounding our unit on inverse trigonometry and integration by parts. This section of the test did not list any other instructions besides evaluating the definite integrals. I've talked to my professor about it and his only response was that I solved it wrong:



To receive full credit, you would have had to evaluate an integral, as the instructions indicated.



Is my interpretation of evaluating the integral different? Does the instruction "Find the antiderivative and then evaluate" not need to exist for that to be required?



Thank you.










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New contributor




user146073 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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  • $begingroup$
    you profesor in mixed up
    $endgroup$
    – Mikey Spivak
    1 hour ago










  • $begingroup$
    can you post the exact problem question?
    $endgroup$
    – Mikey Spivak
    57 mins ago










  • $begingroup$
    @MikeySpivak The question sheet is no longer in my possession, but I remember exactly what it said "Evaluate the following integrals:" (there were several). I wrote the integral exactly as it appeared.
    $endgroup$
    – user146073
    53 mins ago










  • $begingroup$
    He was obviously nitpicking, since you were able to bypass a direct (tedious) evaluation, which is what he wanted.
    $endgroup$
    – herb steinberg
    49 mins ago










  • $begingroup$
    @herbsteinberg Would I be justified to go higher up in the math department with this? In a course where every point matters?
    $endgroup$
    – user146073
    47 mins ago
















3












$begingroup$


I am a freshman enrolled at an American University. Recently, I took an examination in which the following problem appeared:



Evaluate the following integral:



$int_0^4sqrt{16-x^2}dx$



My answer: 4$pi$, was correct. However, I received reduced credit for this answer because I did not solve it correctly (according to the professor). The exams are time-limited and have a fair amount of content, so when I saw this problem, I noticed it was the equation of the top half of a circle centered at (0, 0) and with radius 4. Knowing this, and my knowledge of the integral indicating the signed area under a curve, I merely took the area of a quarter-circle of radius 4, $frac{1}{4}$$pi$$r^2$ and wrote my answer of 4$pi$.



The context of the test was surrounding our unit on inverse trigonometry and integration by parts. This section of the test did not list any other instructions besides evaluating the definite integrals. I've talked to my professor about it and his only response was that I solved it wrong:



To receive full credit, you would have had to evaluate an integral, as the instructions indicated.



Is my interpretation of evaluating the integral different? Does the instruction "Find the antiderivative and then evaluate" not need to exist for that to be required?



Thank you.










share|cite|improve this question







New contributor




user146073 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$












  • $begingroup$
    you profesor in mixed up
    $endgroup$
    – Mikey Spivak
    1 hour ago










  • $begingroup$
    can you post the exact problem question?
    $endgroup$
    – Mikey Spivak
    57 mins ago










  • $begingroup$
    @MikeySpivak The question sheet is no longer in my possession, but I remember exactly what it said "Evaluate the following integrals:" (there were several). I wrote the integral exactly as it appeared.
    $endgroup$
    – user146073
    53 mins ago










  • $begingroup$
    He was obviously nitpicking, since you were able to bypass a direct (tedious) evaluation, which is what he wanted.
    $endgroup$
    – herb steinberg
    49 mins ago










  • $begingroup$
    @herbsteinberg Would I be justified to go higher up in the math department with this? In a course where every point matters?
    $endgroup$
    – user146073
    47 mins ago














3












3








3





$begingroup$


I am a freshman enrolled at an American University. Recently, I took an examination in which the following problem appeared:



Evaluate the following integral:



$int_0^4sqrt{16-x^2}dx$



My answer: 4$pi$, was correct. However, I received reduced credit for this answer because I did not solve it correctly (according to the professor). The exams are time-limited and have a fair amount of content, so when I saw this problem, I noticed it was the equation of the top half of a circle centered at (0, 0) and with radius 4. Knowing this, and my knowledge of the integral indicating the signed area under a curve, I merely took the area of a quarter-circle of radius 4, $frac{1}{4}$$pi$$r^2$ and wrote my answer of 4$pi$.



The context of the test was surrounding our unit on inverse trigonometry and integration by parts. This section of the test did not list any other instructions besides evaluating the definite integrals. I've talked to my professor about it and his only response was that I solved it wrong:



To receive full credit, you would have had to evaluate an integral, as the instructions indicated.



Is my interpretation of evaluating the integral different? Does the instruction "Find the antiderivative and then evaluate" not need to exist for that to be required?



Thank you.










share|cite|improve this question







New contributor




user146073 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$




I am a freshman enrolled at an American University. Recently, I took an examination in which the following problem appeared:



Evaluate the following integral:



$int_0^4sqrt{16-x^2}dx$



My answer: 4$pi$, was correct. However, I received reduced credit for this answer because I did not solve it correctly (according to the professor). The exams are time-limited and have a fair amount of content, so when I saw this problem, I noticed it was the equation of the top half of a circle centered at (0, 0) and with radius 4. Knowing this, and my knowledge of the integral indicating the signed area under a curve, I merely took the area of a quarter-circle of radius 4, $frac{1}{4}$$pi$$r^2$ and wrote my answer of 4$pi$.



The context of the test was surrounding our unit on inverse trigonometry and integration by parts. This section of the test did not list any other instructions besides evaluating the definite integrals. I've talked to my professor about it and his only response was that I solved it wrong:



To receive full credit, you would have had to evaluate an integral, as the instructions indicated.



Is my interpretation of evaluating the integral different? Does the instruction "Find the antiderivative and then evaluate" not need to exist for that to be required?



Thank you.







calculus integration






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user146073 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|cite|improve this question







New contributor




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Check out our Code of Conduct.









share|cite|improve this question




share|cite|improve this question






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asked 1 hour ago









user146073user146073

161




161




New contributor




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New contributor





user146073 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






user146073 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












  • $begingroup$
    you profesor in mixed up
    $endgroup$
    – Mikey Spivak
    1 hour ago










  • $begingroup$
    can you post the exact problem question?
    $endgroup$
    – Mikey Spivak
    57 mins ago










  • $begingroup$
    @MikeySpivak The question sheet is no longer in my possession, but I remember exactly what it said "Evaluate the following integrals:" (there were several). I wrote the integral exactly as it appeared.
    $endgroup$
    – user146073
    53 mins ago










  • $begingroup$
    He was obviously nitpicking, since you were able to bypass a direct (tedious) evaluation, which is what he wanted.
    $endgroup$
    – herb steinberg
    49 mins ago










  • $begingroup$
    @herbsteinberg Would I be justified to go higher up in the math department with this? In a course where every point matters?
    $endgroup$
    – user146073
    47 mins ago


















  • $begingroup$
    you profesor in mixed up
    $endgroup$
    – Mikey Spivak
    1 hour ago










  • $begingroup$
    can you post the exact problem question?
    $endgroup$
    – Mikey Spivak
    57 mins ago










  • $begingroup$
    @MikeySpivak The question sheet is no longer in my possession, but I remember exactly what it said "Evaluate the following integrals:" (there were several). I wrote the integral exactly as it appeared.
    $endgroup$
    – user146073
    53 mins ago










  • $begingroup$
    He was obviously nitpicking, since you were able to bypass a direct (tedious) evaluation, which is what he wanted.
    $endgroup$
    – herb steinberg
    49 mins ago










  • $begingroup$
    @herbsteinberg Would I be justified to go higher up in the math department with this? In a course where every point matters?
    $endgroup$
    – user146073
    47 mins ago
















$begingroup$
you profesor in mixed up
$endgroup$
– Mikey Spivak
1 hour ago




$begingroup$
you profesor in mixed up
$endgroup$
– Mikey Spivak
1 hour ago












$begingroup$
can you post the exact problem question?
$endgroup$
– Mikey Spivak
57 mins ago




$begingroup$
can you post the exact problem question?
$endgroup$
– Mikey Spivak
57 mins ago












$begingroup$
@MikeySpivak The question sheet is no longer in my possession, but I remember exactly what it said "Evaluate the following integrals:" (there were several). I wrote the integral exactly as it appeared.
$endgroup$
– user146073
53 mins ago




$begingroup$
@MikeySpivak The question sheet is no longer in my possession, but I remember exactly what it said "Evaluate the following integrals:" (there were several). I wrote the integral exactly as it appeared.
$endgroup$
– user146073
53 mins ago












$begingroup$
He was obviously nitpicking, since you were able to bypass a direct (tedious) evaluation, which is what he wanted.
$endgroup$
– herb steinberg
49 mins ago




$begingroup$
He was obviously nitpicking, since you were able to bypass a direct (tedious) evaluation, which is what he wanted.
$endgroup$
– herb steinberg
49 mins ago












$begingroup$
@herbsteinberg Would I be justified to go higher up in the math department with this? In a course where every point matters?
$endgroup$
– user146073
47 mins ago




$begingroup$
@herbsteinberg Would I be justified to go higher up in the math department with this? In a course where every point matters?
$endgroup$
– user146073
47 mins ago










4 Answers
4






active

oldest

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2












$begingroup$

An argument could be made that you should include a proof that the integral evaluates the area of a half-disk, rather than just asserting the answer.



Whether you “should” have gotten full points is more a matter of pedagogy than of mathematics, but as a practical tip: using (correct) method Y to solve a problem with instructions to use method X (especially in an intro class and when you are not familiar with the instructor and their teaching philosophy) is always a gamble.






share|cite|improve this answer









$endgroup$





















    1












    $begingroup$

    As a student who has had a similar thing happen and heard of it happening to others, my personal recommendation would be to not bring it up again, it will probably be a losing battle. :(



    But I would not consider your method "wrong" or "incorrect." There are many ways to solve a problem, you simply just made use of one of them, that wasn't the desired one.



    As long as you explained how you came to your answer, the reason why your professor $textit{probably}$ marked you down is that based on the class and section the test covered, the question was designed so that you would display and make use of your knowledge of trig substitution to solve the problem.



    I would hope your professor didn't take too many points off (since the method does work), but in these classes you will usually be expected to give the professor a specific method that they are looking for.






    share|cite|improve this answer









    $endgroup$





















      0












      $begingroup$


      I noticed it was the equation of the top half of a circle centered at (0, 0) and with radius 4. Knowing this, and my knowledge of the integral indicating the signed area under a curve, I merely took the area of a quarter-circle of radius 4, $frac{1}{4}$$pi$$r^2$ and wrote my answer of 4$pi$.




      Did you write this clearly in your test (as you did here)? If not, it is fair to give reduced points. One should always explain where answers come from. If yes, proceed reading.




      To receive full credit, you would have had to evaluate an integral, as the instructions indicated.




      Do the instructions clearly disallow your solution? If not, it was not fair to you, and you should insist on it. If yes, read further.



      Were these instructions available a priori, or they were included in the test itself? If available a priori, you should have complained about them before the test. If not, the instructions are unfair, and you should try to insist about it as well.



      Also, recall that most of this is up to the professor, so you might be with bad luck, sadly.






      share|cite|improve this answer









      $endgroup$





















        0












        $begingroup$

        I've done some undergraduate teaching and my policy is always if you get the correct answer by any means then you get full credit, but others have different policies and it's really up to them.



        You could argue your case. Your professor could argue back that solving the integral by trig substitution does not require the formula $A = pi r^2$, and he did not permit the use of that formula. He could argue that using that formula entails circular reasoning (the formula for the area of a circle has to be gotten by some limiting or integration method equivalent to evaluating $int_{-r}^r sqrt{r^2-x^2}dx$).



        It could go either way for you. But I think it would be a waste of your and your professor's time.






        share|cite









        $endgroup$













          Your Answer





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          4 Answers
          4






          active

          oldest

          votes








          4 Answers
          4






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          2












          $begingroup$

          An argument could be made that you should include a proof that the integral evaluates the area of a half-disk, rather than just asserting the answer.



          Whether you “should” have gotten full points is more a matter of pedagogy than of mathematics, but as a practical tip: using (correct) method Y to solve a problem with instructions to use method X (especially in an intro class and when you are not familiar with the instructor and their teaching philosophy) is always a gamble.






          share|cite|improve this answer









          $endgroup$


















            2












            $begingroup$

            An argument could be made that you should include a proof that the integral evaluates the area of a half-disk, rather than just asserting the answer.



            Whether you “should” have gotten full points is more a matter of pedagogy than of mathematics, but as a practical tip: using (correct) method Y to solve a problem with instructions to use method X (especially in an intro class and when you are not familiar with the instructor and their teaching philosophy) is always a gamble.






            share|cite|improve this answer









            $endgroup$
















              2












              2








              2





              $begingroup$

              An argument could be made that you should include a proof that the integral evaluates the area of a half-disk, rather than just asserting the answer.



              Whether you “should” have gotten full points is more a matter of pedagogy than of mathematics, but as a practical tip: using (correct) method Y to solve a problem with instructions to use method X (especially in an intro class and when you are not familiar with the instructor and their teaching philosophy) is always a gamble.






              share|cite|improve this answer









              $endgroup$



              An argument could be made that you should include a proof that the integral evaluates the area of a half-disk, rather than just asserting the answer.



              Whether you “should” have gotten full points is more a matter of pedagogy than of mathematics, but as a practical tip: using (correct) method Y to solve a problem with instructions to use method X (especially in an intro class and when you are not familiar with the instructor and their teaching philosophy) is always a gamble.







              share|cite|improve this answer












              share|cite|improve this answer



              share|cite|improve this answer










              answered 37 mins ago









              user7530user7530

              34.9k761113




              34.9k761113























                  1












                  $begingroup$

                  As a student who has had a similar thing happen and heard of it happening to others, my personal recommendation would be to not bring it up again, it will probably be a losing battle. :(



                  But I would not consider your method "wrong" or "incorrect." There are many ways to solve a problem, you simply just made use of one of them, that wasn't the desired one.



                  As long as you explained how you came to your answer, the reason why your professor $textit{probably}$ marked you down is that based on the class and section the test covered, the question was designed so that you would display and make use of your knowledge of trig substitution to solve the problem.



                  I would hope your professor didn't take too many points off (since the method does work), but in these classes you will usually be expected to give the professor a specific method that they are looking for.






                  share|cite|improve this answer









                  $endgroup$


















                    1












                    $begingroup$

                    As a student who has had a similar thing happen and heard of it happening to others, my personal recommendation would be to not bring it up again, it will probably be a losing battle. :(



                    But I would not consider your method "wrong" or "incorrect." There are many ways to solve a problem, you simply just made use of one of them, that wasn't the desired one.



                    As long as you explained how you came to your answer, the reason why your professor $textit{probably}$ marked you down is that based on the class and section the test covered, the question was designed so that you would display and make use of your knowledge of trig substitution to solve the problem.



                    I would hope your professor didn't take too many points off (since the method does work), but in these classes you will usually be expected to give the professor a specific method that they are looking for.






                    share|cite|improve this answer









                    $endgroup$
















                      1












                      1








                      1





                      $begingroup$

                      As a student who has had a similar thing happen and heard of it happening to others, my personal recommendation would be to not bring it up again, it will probably be a losing battle. :(



                      But I would not consider your method "wrong" or "incorrect." There are many ways to solve a problem, you simply just made use of one of them, that wasn't the desired one.



                      As long as you explained how you came to your answer, the reason why your professor $textit{probably}$ marked you down is that based on the class and section the test covered, the question was designed so that you would display and make use of your knowledge of trig substitution to solve the problem.



                      I would hope your professor didn't take too many points off (since the method does work), but in these classes you will usually be expected to give the professor a specific method that they are looking for.






                      share|cite|improve this answer









                      $endgroup$



                      As a student who has had a similar thing happen and heard of it happening to others, my personal recommendation would be to not bring it up again, it will probably be a losing battle. :(



                      But I would not consider your method "wrong" or "incorrect." There are many ways to solve a problem, you simply just made use of one of them, that wasn't the desired one.



                      As long as you explained how you came to your answer, the reason why your professor $textit{probably}$ marked you down is that based on the class and section the test covered, the question was designed so that you would display and make use of your knowledge of trig substitution to solve the problem.



                      I would hope your professor didn't take too many points off (since the method does work), but in these classes you will usually be expected to give the professor a specific method that they are looking for.







                      share|cite|improve this answer












                      share|cite|improve this answer



                      share|cite|improve this answer










                      answered 46 mins ago









                      HotdogHotdog

                      627




                      627























                          0












                          $begingroup$


                          I noticed it was the equation of the top half of a circle centered at (0, 0) and with radius 4. Knowing this, and my knowledge of the integral indicating the signed area under a curve, I merely took the area of a quarter-circle of radius 4, $frac{1}{4}$$pi$$r^2$ and wrote my answer of 4$pi$.




                          Did you write this clearly in your test (as you did here)? If not, it is fair to give reduced points. One should always explain where answers come from. If yes, proceed reading.




                          To receive full credit, you would have had to evaluate an integral, as the instructions indicated.




                          Do the instructions clearly disallow your solution? If not, it was not fair to you, and you should insist on it. If yes, read further.



                          Were these instructions available a priori, or they were included in the test itself? If available a priori, you should have complained about them before the test. If not, the instructions are unfair, and you should try to insist about it as well.



                          Also, recall that most of this is up to the professor, so you might be with bad luck, sadly.






                          share|cite|improve this answer









                          $endgroup$


















                            0












                            $begingroup$


                            I noticed it was the equation of the top half of a circle centered at (0, 0) and with radius 4. Knowing this, and my knowledge of the integral indicating the signed area under a curve, I merely took the area of a quarter-circle of radius 4, $frac{1}{4}$$pi$$r^2$ and wrote my answer of 4$pi$.




                            Did you write this clearly in your test (as you did here)? If not, it is fair to give reduced points. One should always explain where answers come from. If yes, proceed reading.




                            To receive full credit, you would have had to evaluate an integral, as the instructions indicated.




                            Do the instructions clearly disallow your solution? If not, it was not fair to you, and you should insist on it. If yes, read further.



                            Were these instructions available a priori, or they were included in the test itself? If available a priori, you should have complained about them before the test. If not, the instructions are unfair, and you should try to insist about it as well.



                            Also, recall that most of this is up to the professor, so you might be with bad luck, sadly.






                            share|cite|improve this answer









                            $endgroup$
















                              0












                              0








                              0





                              $begingroup$


                              I noticed it was the equation of the top half of a circle centered at (0, 0) and with radius 4. Knowing this, and my knowledge of the integral indicating the signed area under a curve, I merely took the area of a quarter-circle of radius 4, $frac{1}{4}$$pi$$r^2$ and wrote my answer of 4$pi$.




                              Did you write this clearly in your test (as you did here)? If not, it is fair to give reduced points. One should always explain where answers come from. If yes, proceed reading.




                              To receive full credit, you would have had to evaluate an integral, as the instructions indicated.




                              Do the instructions clearly disallow your solution? If not, it was not fair to you, and you should insist on it. If yes, read further.



                              Were these instructions available a priori, or they were included in the test itself? If available a priori, you should have complained about them before the test. If not, the instructions are unfair, and you should try to insist about it as well.



                              Also, recall that most of this is up to the professor, so you might be with bad luck, sadly.






                              share|cite|improve this answer









                              $endgroup$




                              I noticed it was the equation of the top half of a circle centered at (0, 0) and with radius 4. Knowing this, and my knowledge of the integral indicating the signed area under a curve, I merely took the area of a quarter-circle of radius 4, $frac{1}{4}$$pi$$r^2$ and wrote my answer of 4$pi$.




                              Did you write this clearly in your test (as you did here)? If not, it is fair to give reduced points. One should always explain where answers come from. If yes, proceed reading.




                              To receive full credit, you would have had to evaluate an integral, as the instructions indicated.




                              Do the instructions clearly disallow your solution? If not, it was not fair to you, and you should insist on it. If yes, read further.



                              Were these instructions available a priori, or they were included in the test itself? If available a priori, you should have complained about them before the test. If not, the instructions are unfair, and you should try to insist about it as well.



                              Also, recall that most of this is up to the professor, so you might be with bad luck, sadly.







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                              share|cite|improve this answer










                              answered 20 mins ago









                              Pedro APedro A

                              2,0461827




                              2,0461827























                                  0












                                  $begingroup$

                                  I've done some undergraduate teaching and my policy is always if you get the correct answer by any means then you get full credit, but others have different policies and it's really up to them.



                                  You could argue your case. Your professor could argue back that solving the integral by trig substitution does not require the formula $A = pi r^2$, and he did not permit the use of that formula. He could argue that using that formula entails circular reasoning (the formula for the area of a circle has to be gotten by some limiting or integration method equivalent to evaluating $int_{-r}^r sqrt{r^2-x^2}dx$).



                                  It could go either way for you. But I think it would be a waste of your and your professor's time.






                                  share|cite









                                  $endgroup$


















                                    0












                                    $begingroup$

                                    I've done some undergraduate teaching and my policy is always if you get the correct answer by any means then you get full credit, but others have different policies and it's really up to them.



                                    You could argue your case. Your professor could argue back that solving the integral by trig substitution does not require the formula $A = pi r^2$, and he did not permit the use of that formula. He could argue that using that formula entails circular reasoning (the formula for the area of a circle has to be gotten by some limiting or integration method equivalent to evaluating $int_{-r}^r sqrt{r^2-x^2}dx$).



                                    It could go either way for you. But I think it would be a waste of your and your professor's time.






                                    share|cite









                                    $endgroup$
















                                      0












                                      0








                                      0





                                      $begingroup$

                                      I've done some undergraduate teaching and my policy is always if you get the correct answer by any means then you get full credit, but others have different policies and it's really up to them.



                                      You could argue your case. Your professor could argue back that solving the integral by trig substitution does not require the formula $A = pi r^2$, and he did not permit the use of that formula. He could argue that using that formula entails circular reasoning (the formula for the area of a circle has to be gotten by some limiting or integration method equivalent to evaluating $int_{-r}^r sqrt{r^2-x^2}dx$).



                                      It could go either way for you. But I think it would be a waste of your and your professor's time.






                                      share|cite









                                      $endgroup$



                                      I've done some undergraduate teaching and my policy is always if you get the correct answer by any means then you get full credit, but others have different policies and it's really up to them.



                                      You could argue your case. Your professor could argue back that solving the integral by trig substitution does not require the formula $A = pi r^2$, and he did not permit the use of that formula. He could argue that using that formula entails circular reasoning (the formula for the area of a circle has to be gotten by some limiting or integration method equivalent to evaluating $int_{-r}^r sqrt{r^2-x^2}dx$).



                                      It could go either way for you. But I think it would be a waste of your and your professor's time.







                                      share|cite












                                      share|cite



                                      share|cite










                                      answered 8 mins ago









                                      D_SD_S

                                      13.8k61552




                                      13.8k61552






















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