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?
The animation featured here (originally posted at mathani.tumblr.com, but based on this post by math visualization guru Lucas) gives us the answer.
Writes Lucas on his captivating math-visualization tumblr, 1ucasvb:
For the rest of the story: http://io9.com/what-does-a-hearts-sine-function-look-like-512271634