Evaluate:

To find:

Formula Used:

1.

2. sec² x = 1 + tan² x

Dividing the given equation by cos²x in the numerator and denominator gives us,

… (1)

Let y = tan x

dy = sec² x dx … (2)

Also, y² = tan² x

i.e., y² = sec² x – 1

sec² x = y² + 1 … (3)

Substituting (2) and (3) in (1),

Since y = tan x,

Therefore,