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?