Introduction to The Sine Wave Function

The Sine is a function that, in terms of a triangle's vertices, expresses the ratio of the vertex opposite to the angle we're getting the sine of, over the hypotenuse.

It's written as

When we have an angle we can also use that in this function. In terms of calculus, this function becomes For now, we're just explaining what it is. Its "brother" function is what we'll define next:
Introduction to The Cosine Wave Function