Solve equation using the sum and difference formulas

The video tutorial explains the sum and difference formulas for trigonometric functions, focusing on sine and cosine. The instructor demonstrates how to apply these formulas to solve problems, emphasizing the importance of understanding positive and negative signs in the formulas. The tutorial also covers evaluating trigonometric functions using the unit circle and finding solutions for sine of X within a specified range. The instructor provides step-by-step guidance and clarifies common misconceptions.

How does the teacher evaluate cosine of π / 3?

For which angle is sine equal to 1, as mentioned in the discussion?