Given:

Adding (1) and (2), we get

Here, if f(x) = log (sin x) and f(π – x)=log ( sin (π –x))= log (sin x ) = f(x)

Adding (1) and (2), we get

Let 2x = t ⇒ 2dx = dt

When x = 0, t = 0 and when x = π /2, t = π