Trigonometry, worked out

The Unit Circle

Angles and the sides of triangles. Use SOH-CAH-TOA in a right triangle, find the exact values of the special angles, go round the unit circle with reference angles and signs, solve any triangle with the laws of sines and cosines, and graph sine and cosine waves — with the reason for every step.

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The work

Say it out loud

    Special angles are worked out exactly, with square roots (√3/2, not 0.866…); other angles use the calculator, and the rounding is always said. Triangles without trig? See the Shape Shop. Graphs of other functions are on the Graph Paper.