Memorize sine, cosine, and tangent at 0°, 30°, 45°, 60°, and 90°. Those five angles show up constantly. sin 30° = 1/2. cos 60° = 1/2. tan 45° = 1. The ratio definitions are in SOH-CAH-TOA.
The short list
0°: sin 0, cos 1, tan 0. 90°: sin 1, cos 0, tan undefined. 30-60-90 sides give the 30° and 60° values, in 30-60-90 triangles. 45-45-90 gives 45°, in 45-45-90 triangles.
Reciprocals of these values are in reciprocal trig identities.
The bottom line
Five angles, three functions. Write them once on scratch paper if you freeze.
Start practicing
Start with a free diagnostic, then drill your weak spots with 15-question quizzes and track how you're doing across Reading, English, and Math. Compare plans whenever you're ready to go further.
This article offers general ACT prep guidance. The ACT can change from year to year, including its format, scoring, policies, test dates, and fees, so always confirm the latest details on the official ACT website at act.org before you make decisions. ACT® is a registered trademark of ACT, Inc. thirty-six is not affiliated with, endorsed by, or sponsored by ACT.