Right Triangle Definitions for Trigonometry Functions

By Mary Jane Sterling

Part of Trigonometry For Dummies Cheat Sheet

The basic trig functions can be defined with ratios created by dividing the lengths of the sides of a right triangle in a specific order. The label hypotenuse always remains the same — it’s the longest side. But the designations of opposite and adjacent can change — depending on which angle you’re referring to at the time. The opposite side is always that side that doesn’t help make up the angle, and the adjacent side is always one of the sides of the angle.