Learn how to evaluate using the sum formula of two angles cosine

The video tutorial explains the cosine formula and how to break down angles for evaluation. It covers the importance of understanding the unit circle and how to evaluate angles in different quadrants. The tutorial also demonstrates simplifying trigonometric expressions using algebraic methods, emphasizing the need to know the unit circle and trigonometric identities.

What role does the unit circle play in evaluating trigonometric functions?

Explain the process of simplifying the expression involving sine and cosine as described in the text.