Students identify DeMoivre's Theorem. In this precalculus lesson, students derive the law of sine and cosine as it relates to DeMoivre's Theorem. They identify the best time to use these formulas.

This Math Forum site contains a brief proof of De Moivre's Theorem ((cos(x)+isin(x))^n = cos(nx) + isin(nx)) Where n is an integer.