Circular function in the context of Similarity (geometry)

In mathematics, an argument of a function is a value provided to obtain the function's result. It is also called an independent variable.

For example, the binary function ${\displaystyle f(x,y)=x^{2}+y^{2}}$ has two arguments, ${\displaystyle x}$ and ${\displaystyle y}$, in an ordered pair ${\displaystyle (x,y)}$. The hypergeometric function is an example of a four-argument function. The number of arguments that a function takes is called the arity of the function. A function that takes a single argument as input, such as ${\displaystyle f(x)=x^{2}}$, is called a unary function. A function of two or more variables is considered to have a domain consisting of ordered pairs or tuples of argument values. The argument of a circular function is an angle. The argument of a hyperbolic function is a hyperbolic angle.