Unit circle – sine, cosine and tangent of any angle

MathematicsTrigonometryAges 16–17

Drag point M around the unit circle (radius 1) to change the angle θ; the reference triangle and the tangent segment on the tangent line show sin, cos and tan of θ at once. Angles are measured in degrees or radians, and full turns are counted when you drag past 360°/−360°. The graph alongside plots the exact sin, cos or tan function against the angle with a marker moving in sync, and you can drag it directly on the graph. Turn on special-angle snapping to make the point snap to 30°, 45°, 60°… and see the exact trigonometric values in surd form. Based on the "Trig Tour" simulation by PhET Interactive Simulations, University of Colorado Boulder (CC BY 4.0); rewritten.

Lesson: Trigonometric functions of any angle