Evaluate:

Let … (1)

We know that

… (2)

Adding (1) and (2), we get

We know that

Dividing numerator and denominator by cos² x, we get

Putting b tan x = p

⇒ b sec² x dx = dp

⇒ sec² x dx = dp/b

When x = 0, then p = 0 and when x = π/2, then p = ∞

We know that