Q38 / 90 · JEE Main 2021 (24 Feb Shift 1) · Mathematics

If ∫cosx-sinx8-sin2x dx=asin-1sinx+cosx b+c, where c is a constant of integration, then the ordered pair a,b is equal to:

  • A
    1,-3
  • B
    3,1
  • C
    -1,3
  • Correct answer
    D
    1,3

Solution

∫cosx-sinx8-sin2xdx

=∫cosx-sinx9-sinx+cosx2dx

Let sinx+cosx=t

∫dt9-t2=sin-1t3+c

=sin-1sinx+cosx3+c

So a=1, b=3

Hence, the correct answer is option: 'D'.

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