## Algebraic Cosine

#### Problem

Given that $x$ is a rational multiple of $\pi$, prove that $cos(x)$ is algebraic.

Problem ID: 369 (30 Nov 2009) Difficulty: 4 Star

Given that $x$ is a rational multiple of $\pi$, prove that $cos(x)$ is algebraic.

Problem ID: 369 (30 Nov 2009) Difficulty: 4 Star