This question already has an answer here:
No doubt as some people have already seen, today morning wolfram posted the best valentine ever. The graph depicting cupid with its arrow and floating hearts around it involves something like 6 pages of parametric equations. My question to this community is, does any one have any idea how these equations were discovered? Is there a methodology here when people post equations with graphs looking like bunnies or hearts or is it just playing around with trigonometric functions with a little bit of intelligent guessing until something interesting pops out? Are there an papers/books/references on these type of derivations? No doubt these have been done for a while. I hope somebody at wolfram will publish something soon.