EDUCATION TOOL
Unit Circle Reference
An interactive unit circle showing sine, cosine, and tangent for any angle.
Radians
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About this tool
Drag the slider to any angle and see its exact position on the unit circle, along with sine, cosine, and tangent values updating live — a visual reference for trigonometry that connects the numbers to the geometry.
Frequently asked questions
- What is the unit circle?
- A circle with radius 1 centered at the origin. For any angle θ measured from the positive x-axis, the point on the circle has coordinates (cos θ, sin θ) — which is exactly why those functions are defined the way they are.
- Why does tan(θ) sometimes show "undefined"?
- Tangent is sine divided by cosine, so it's undefined whenever cosine is exactly zero — at 90° and 270°, where the tangent line would be vertical.
- What units are the angle values in?
- The slider uses degrees, with the exact radian equivalent shown alongside it (radians = degrees × π / 180).