Prove $\sin ( x + y ) + \sin ( x - y ) = 2 \sin x \cos y$

question 37

Essay

Prove $\sin ( x + y ) + \sin ( x - y ) = 2 \sin x \cos y$ .

---

Definitions:

Degree of Association

A statistical measure that describes the level or strength of a relationship between two or more variables.

Correlation

A mathematical indicator showing how much two or more variables move in relation to each other.

Consistent Measurement

Involves the use of precise and stable methods or instruments to obtain reliable data across different instances or over time.

Reliability

Consistency, either within a scale or over time.