Sine
From Conservapedia
Sine is a trigonometric function describing the ratio between the opposite side and the hypotenuse in a right triangle. As a function it is usually abbreviated sin.
Sine Graph
The basic sine graph is as follows:

That would be a full period of the graph  as 2π radians is equivalent to one circle. The graph continues in that pattern.
Relationship to cosine and cosecant
A mathematical identity involving sine is: