To find:

Formula used:

1. sec² x = 1 + tan²x

2.

Dividing by cos⁴ x in the numerator and denominator of the given equation,

Let y = tan x

dy = sec² x dx

Substituting in the original equation,

Dividing by y² in the numerator and denominator,

Let

Therefore,

Substituting for z,

Substituting for y = tan x,

Therefore,