Cosine

Note: In this series A is in radians.

Note: Valid for 0 ≤ A ≤ π/2

Note: Valid for 0 ≤ A ≤ π/2

The following expression is also known as the half angle formula:

Inverse trigonometric functions

Inverse trigonometric functions are often written as arccos(A) or cos^-1(A)

Note: Valid for 0 ≤ A ≤ π/2

See also: Cosecant, Cotangent, Secant, Series Expansions, Sine, Tangent.