Trigonometry Examples

$\cos (x) \cos (3 x) + \sin (- x) \sin (3 x)$

Step 1

Graph.

$\cos (x) \cos (3 x) + \sin (- x) \sin (3 x)$

Step 2

$[\begin{array}{c} x^{2} & \frac{1}{2} \\ \sqrt{π} & \int x d x \end{array}]$