Write and evaluate expression using sum and difference identities

The video tutorial explains how to solve a trigonometric expression without using a calculator. The teacher guides students through recognizing and applying the sine formula for the difference of two angles. By identifying the relationship in the expression, the teacher demonstrates how to simplify and solve it, emphasizing the sine of 90 degrees equals 1.

What is the sine formula mentioned in the text?

What is the significance of the difference of angles in the sine formula?

How does the teacher recognize the relationship in the problem?

What example does the teacher use to explain the simplification of expressions?

What is the final result of the sine calculation mentioned in the text?