Primitive of Cosine Function

Theorem

 * $\displaystyle \int \cos \left({x}\right) dx = \sin \left({x}\right) + C$

Proof
From Derivative of Sine Function, we have:
 * $\dfrac{d}{dx} \sin \left({x}\right) = \cos \left({x}\right)$

The result follows from the definition of indefinite integral.