Glossary · Phase 2 · Math, when you need it
Unit circle
The circle of radius 1 around the origin. Turning by an angle θ from (1, 0) lands on the point (cos θ, sin θ).
Draw a circle of radius 1 around the origin, the unit circle. Start at the point (1, 0) and turn counterclockwise by an angle θ. The point you land on has coordinates (cos θ, sin θ): the cosine is how far across, and the sine is how far up.
Try it now
As the angle goes round, cosine traces how far across you are and sine how far up. The curve drawn is the sine wave.
Learn it properly
Angles and waves · Radians, sine and cosine on the unit circle, the angle between embeddings, cycles and positions as waves. About 25 minutes.
Other terms from the same lesson
- radian: A unit for angles: the length of arc the angle sweeps on a circle of radius 1. A full turn is 2π radians, about 6.28, and Python's math functions expect radians.
- sine wave: The smooth repeating curve traced by the height of a point going round the unit circle. Its amplitude is how far it swings; its period is how long one cycle takes.
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