# Cosine Identity

- Author:
- Tim Brzezinski

- Topic:
- Cosine

In the applet below, the graph of the function is displayed.
Place the BIG WHITE POINT anywhere you'd like prior to sliding the slider.
Answer the question that follows.

## 1.

Write a new trigonometric identity that expresses the relationship between and .

## 2.

What else can you conclude about the parent cosine function ? For a hint, click here.