# Right Triangles and Trigonometry

# Altitudes and Side Lengths

Before we go around flirting with all the right triangles on the two-dimensional plane (although they *are* quite saucy), we should get down to business. Get to know them first. Find out what they want and need. Build a solid emotional foundation with them. That kind of stuff is important.

The **altitude** of a triangle is the distance from one vertex straight down to the opposite side at a 90° angle. It's basically the height of a triangle. Luckily for us, the two legs of a right triangle are its base and height—or altitude. Not too bad.

But what if we lay the triangle down on its longest side? The altitude is the distance from the 90° angle straight down. How do we find the altitude then? Suddenly, things aren't so peachy anymore.