Pre-Calculus - How to solve using the addition formula of two angles for cosine cos(160)

The video tutorial explains how to calculate the cosine of 165 degrees using the unit circle and sum and difference formulas. It begins with a review of the unit circle and the difficulty of finding the cosine of 160 degrees directly. The instructor then corrects the problem to 165 degrees and demonstrates how to use the sum and difference formulas to find the exact value. The process involves identifying angles that add up to 165 degrees, applying the formulas, and simplifying the result to reach the final answer.

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