Trigonometric Identities

Trigonometric Identities

Identities are equations that are true for all values of the variable.

Pythagorean Identities

• $\sin^2 x + \cos^2 x = 1$
• $1 + \tan^2 x = \sec^2 x$
• $1 + \cot^2 x = \csc^2 x$

Double Angle Identities

• $\sin(2x) = 2\sin x \cos x$
• $\cos(2x) = \cos^2 x - \sin^2 x$

Solved Problems