Primitive of Square of Secant Function

Theorem

 * $\ds \int \sec^2 x \rd x = \tan x + C$

where $C$ is an arbitrary constant.

Proof
From Derivative of Tangent Function:
 * $\map {\dfrac \d {\d x} } {\tan x} = \sec^2 x$

The result follows from the definition of primitive.

Also see

 * Primitive of Square of Cosecant Function