If I = 2 π ∫ - π 4 π 4 d x 1 + e s i n x 2 - c o s 2 x then find 27 I 2 equals____

If I=2π-π4π4dx1+esinx2-cos2x then find 27I2 equals____

Solution

I=2π-π4π411+esinx2-cos2xdx
Using -aafxdx=0afx+f-xdx
I=2π0π411+esinx2-cos2x+11+e-sinx2-cos2xdx
I=2π0π411+esinx2-cos2x+esinxesinx+12-cos2xdx
I=2π0π4dx2-cos2x
I=2π0π4dx2-1-tan2x1+tan2x=2π0π41+tan2xdx1+3tan2x
I=2π0π4sec2xdx1+3tan2x
Put tan x=t
sec2xdx=dt 
and when x=0t=0
x=π4t=1
I=2π01dt1+3t2
I=2π01dt1+3t2
I=2π13tan-13t01          01dxa2+x2=1atan-1xa+C
I=23πtan-13-tan-10
I=23π×π3
I=233
27I2=27×427=4

Asked in: JEE Advanced 2019 (Paper 1)

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