This treatment of trigonometry will be unlike any you've seen before. We'll equate sine and cosine to points on a bicycle wheel, giving you a deeply geometric intuition for trigonometric formulas.

By the end of these quizzes, you know your trig identities and how to derive new ones.

Four thousand years ago, the Babylonians divided the ecliptic (the path of the sun relative to the Earth) into 360 degrees; this is why we still divide circles into 360 degrees today. However, there are more natural ways to measure angles, such as radians, which are covered in these quizzes:

What sine and cosine identities are implied by this diagram?