The integral ∫ π 4 3 π 4 d x 1 + cos x is equal to

The integral ∫π43π4dx1+cosx is equal to
  1. -2
  2. 2
  3. 4
  4. -1

Solution

Let, I=∫π43π4dx1+cosx

⇒I=∫π43π4dx1+2cos2x2-1

⇒I=12∫π43π4sec2x2 dx

⇒I=tanx2π43π4

⇒I=tan3π8-tanπ8

⇒I=2+1-2-1

⇒I=2.

Asked in: JEE Main 2017 (02 Apr)

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