# Greek Small Letter Theta

θ
Symbol Format Data
θ Code Point
U+03B8
TeX
\theta
SVG

## Usage

The Greek letter (theta) is used in math as a variable to represent a measured angle. For example, the symbol theta appears in the three main trigonometric functions: sine, cosine, and tangent as the input variable.

In plain language, this represents the cosine function which takes in one argument represented by the variable .

## Related

The capital Greek letter Θ (capital theta).

## Links

The cosine function returns the cosine of an angle provided in radians. In geometric terms, the function returns the ratio of the right-triangle's adjacent side over its hypotenuse.

The sine function returns the sine of a number provided in radians. In geometric terms, the function returns the vertical component of the point formed by the angle on the unit circle.

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