Pythagorean Identity

The fundamental trigonometric identity.

sin^{2} θ + cos^{2} θ = 1

Variables

On the unit circle a point is $(cos θ, sin θ)$ , and its distance from the origin is 1. Dividing by $cos^{2} θ$ gives $1 + tan^{2} θ = sec^{2} θ$ .

If $sin θ = \frac{3}{5}$ in quadrant I, then $cos θ = \frac{4}{5}$ .

Simplify algebraic, rational, exponential, logarithmic and trigonometric expressions step by step.

Law of Sines

Relates sides to the sines of their opposite angles in any triangle.