# Fundamental Trigonometric Identities. Formulas

## The Fundamental trigonometric identities represent mathematical expressions for trigonometric functions that are valid for all values of the argument (from the common domain of trig functions).

Fundamental trigonometric identities typically include the following expressions:

and

# We can use the Pythagorean identity to solve for sin α or cos α:

We can use the Pythagorean identity to solve for tan α or cot α:

and