I needed to do a bit of math to figure out what fixtures we want to put on the track lighting system in Terry's studio. I found a Right Triangle Calculator that was extremely helpful.

Basically, if you know two facts about your triangle, it will calculate the rest of them for you. For example, I know that the height of my triangle is 88", and that one of the non-90-degree angles is 12.5 degrees. Armed with only that information, the calculator told me how long the hypotenuse and the other side of the triangle are.