The Greek letter (theta) is used in mathematics 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 .
Symbol  Format  Data 

θ  Unicode 

TeX 


SVG 
The cosine function returns the cosine of an angle provided in radians. In geometric terms, the function returns the ratio of the righttriangle'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.
The capital Greek letter Θ (capital theta).