Sin(x)=a/c or b/c depending on the angle

Cos(x)=b/c or a/c depneding on the angle

Tan(X)= a/b or b/a depending on the angle

The best way to remember these formulas is SOH, CAH, TOA

Sin= Opposite/Hypotenuse

Cos= Adjacent/Hypotenuse

Tan= Opposite/Adjacent

sin(2x) = 2 sin x cos x

sin^{^2}(x) + cos^{^2}(x) = 1

tan^{^2}(x) + 1 = sec^{^2}(x)

cot^{^2}(x) + 1 = csc^{^2}(x)