Graph of  trigonometric functions     definition is – a function of an arc or angle most simply expressed in terms of the ratios of pairs of sides of a right-angled triangle —called also circular function.

standard unit circle (a circle with radius 1 unit),  starting at the origin and making some angle with the x -axis, the sine of the angle gives the y -component.

Due to periodicity  in nature of sin and cos function.  Therefore we use for graph of waves

Graphs of Trig Functions

Graph of trigonometric function