What is the input to a trigonometric function? a ratio the x position of a point on the circle a central angle of a circle the y position of a point on the circle

A central angle of a circle

Step-by-step explanation:

The trigonometric functions are also known as circular functions.

The two fundamental trigonometric functions are defined as the coordinates of a any point A  travelling around on the unit circle of radius  1 .

The input variable in trigonometric functions is the central angle of the circle 'x' such that we get sin x and cos x which give the x and y coordinates of A.

Hence, the input to a trigonometric function is a central angle of a circle.