Evaluate : `int_0^(π/2) (cos 2x dx)/(cos x + sin x)`

Explanation

I = int_0^(π/2) (cos 2x dx)/(cosx + sinx) = int_0^(π/2) (cos(π-2x))/(sinx + cosx) dx = -1` therefore `2I = 0 implies I = 0`