Trigonometry — SOH CAH TOA

Only tested at a basic level. No trig identities, no unit circle memorization required.

SOH: sin(angle) = Opposite / Hypotenuse

CAH: cos(angle) = Adjacent / Hypotenuse

TOA: tan(angle) = Opposite / Adjacent

Complementary angle relationship:

sin(x) = cos(90 - x)

If sin(30) = 0.5, then cos(60) = 0.5

SAT question type:

"In triangle ABC, angle B = 90. If sin(A) = 3/5, what is cos(C)?"

A and C are complementary. So cos(C) = sin(A) = 3/5.

Radians: pi radians = 180 degrees. Convert: multiply degrees by pi/180.

Reference:

Wikipedia: Trigonometry

https://en.wikipedia.org/wiki/Trigonometry