# Theta Symbol

The Greek letter theta (θ) is often used as a variable in mathematics to represent an angle. Theta appears in the three main trigonometric functions: cosine, sine, and tangent as an input argument.

Format Display Data
TeX
\theta
Unicode θ
952


## Usage

Sine | Function

Given the angle of a right triangle as input, returns the ratio of the triangle's opposite side over its hypotenuse.

Cosine | Function

Given the angle of a right triangle as input, returns the ratio of the triangle's adjacent side over its hypotenuse.

Tangent | Function

Given the angle of a right triangle as input returns the ratio of the triangle's opposite side over its adjacent side.

Angle | Concept

An angle is defined as the amount of rotation between two rays. Angles are measured using degrees and radians. A full rotation in degrees is 360°. A full rotation in radians is approximately 6.283 radians or τ (tau) radians.