# Right Triangles and Trigonometry Introduction

Your mom has been telling you for the past three months that she doesn't want anything for her birthday. "Just make me something," she says. "It'll mean more to me if it's from the heart." Of course, you know that the only reason she says that is because she knows you can't afford that new massaging spa chair from Brookstone that she's had her eye on.

So you decide to build her a bookcase. Why not? She likes books. And you've certainly gotten tired of tripping over her Danielle Steel novels every time you walk up and down the stairs. Seems like a win-win.

But once you sit down with your carpenter pants and toolbox, you realize that it's not just going to be about taking pre-cut boards and slapping them together with Krazy Glue. You're going to have to cut some of these puppies, fit them into grooves, and compute angles and dimensions and stuff. In other words, you'd better get pretty cozy with geometry or this bookcase is going to look like a set piece from a Tim Burton movie.

We know that geometry can be tougher and drier than your grandma's homemade brisket. Sometimes it seems like all these shapes and proofs and theorems have joined forces to make your life an endless swirling vortex of headaches and anxiety. We know the feeling.

News flash. It doesn't have to be that way. All we have to do is look at geometry from the right…tri-angle. Good one, eh?

We know a right triangle is the opposite of a left triangle, but why does its 90° angle matter so much? Britney Spears really wants us to give her a sign (and then hit her, baby, one more time), but could she have meant "sine" instead? If Law & Order wants to have as many spinoffs as possible, why isn't "Law of Cosines" one of them? We'll answer these questions and many more.

In this unit, we'll get up-close and personal with right triangles, so keep some Tic Tacs handy. Mr. Pythagoras, a gentlemanly fellow, will enlighten us about his theorem, but don't buy into the hype-otenuse. We'll venture straight into the delicious world of trigo-nom-nom-nom-etry and as long as we prove ourselves (and a few other things, like proofs), that bookcase will be done and looking fabulous in no time. Eat your heart out, Brookstone.