Geometry & Trigonometry
Intermediate

Pythagorean Identity

The fundamental trigonometric identity.

Formula

sin⁡2θ+cos⁡2θ=1\sin^2\theta + \cos^2\theta = 1

Variables

\thetaAngle

Example

At θ = 30°: sin²30° + cos²30° = 1/4 + 3/4 = 1. ✓

Did You Know?

sin²θ + cos²θ = 1 is literally the Pythagorean theorem applied to the unit circle.

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