What does a heart's sine function look like?

In high school, you probably learned that trigonometric functions – like sine, cosine and tangent –can be derived, geometrically, from a circle (hence why trig functions are also known as "circular" functions). But what happens if you use a square to derive these functions, instead? Or a triangle? Or a heart? » 6/10/13 7:20am 6/10/13 7:20am