# Free Trigonometry Help

Trying to keep up with trig can be hard at first -- suddenly you're learning new terms like sine, cosine, and tangent, and having to figure out more triangles than you ever cared about. Fortunately it's just like any other math -- follow a set of rules, understand why it works how it does, and you'll be fine. Check out the lessons below if you need a refresher on trigonometry topics.

## Text Lessons

- Addition Formulas
- Derivatives of Trig Functions
- Double/Half Angle Formulas
- Full List of Trigonometric Identities
- Magic Identity
- Basic Trigonometry
- Measuring an Angle
- Product and Sum Formulas
- Pythagorean Identities
- Right Angle Trig
- Tangents and Slope
- Trig Functions
- What is Trigonometry?

#### Featured Lesson

Do you remember the double angle formulas?