Prove that

…(1)

Use King theorem of definite integral

…(2)

Adding eq.(1) and eq.(2)

We break it in two parts

Let, tan x = t

⇒ sec²x dx = dt

At x = 0, t = 0

At x = π, t = 0

We know that when upper and lower limit is same in definite

integral then value of integration is 0.

So, y = 0