Cosine of Integer Multiple of Argument/Formulation 5/Examples/Cosine of Quintuple Angle

Example of Use of Cosine of Integer Multiple of Argument/Formulation 5

 * $\cos 5 \theta = \cos \theta + 2 \cos \theta \paren {\cos 4 \theta - \cos 2 \theta}$

Proof
Follows directly from the Cosine of Integer Multiple of Argument/Formulation 5:

Explicit derivation illustrated below: