## 17Calculus Precalculus - Unit Circle

##### 17Calculus

The Unit Circle

All of trigonometry is based on the unit circle. So it is important for you to understand the following figure and commit it to memory.

The Unit Circle [ source: wikipedia ]

Here is a good video that shows where some of the information in this figure comes from.

### Krista King Math - The Unit Circle [18min-15secs]

video by Krista King Math

There is a lot of information here, so here is a video that help you remember what you need to.

### PatrickJMT - A Way to Remember the Entire Unit Circle for Trigonometry [7min-18secs]

video by PatrickJMT

Okay, so now you know the basics of trigonometry, right triangles and the unit circle. Next, let's take a look at some trig identities. Identities are equations that are true for every angle in a circle. There are many, many trig identities. On the next page, we list a few that are used a lot. You will need to commit these equations to memory. The best way to remember them is not to memorize them but to use them a lot in practice problems.

When using the material on this site, check with your instructor to see what they require. Their requirements come first, so make sure your notation and work follow their specifications.

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