Mechanical Unit Circle and Trig Functions

A fully mechanical unit circle: turn the handle to an angle and sliders move along the sine, cosine and tangent graphs to show their values. Move a slider instead, and the angle and the other graphs follow.

It ties the circle and the graphs together in a way a textbook diagram cannot.

Design by Devin Ho on Printables, shared under CC BY 4.0. The files and photos are the designer's, unchanged.

1. Print the face plates, sliders, racks and the 10- and 20-tooth gears; choose the face with degrees or without.
2. Assemble following the numbered files.
3. Students find angles where sin = cos, where tan is undefined, and where sine is negative.