This document discusses the trigonometric relationships SOH CAH TOA, which are used to find unknown sides of a right triangle based on a known side and the trigonometric function (sine, cosine, or tangent) of one of the angles. It explains that sine is opposite over hypotenuse, cosine is adjacent over hypotenuse, and tangent is opposite over adjacent. The document provides an example of using SOH CAH TOA to solve for an unknown side of a right triangle given one of the angle measures and a known side. It recommends memorizing and using SOH CAH TOA whenever working with right triangles in trigonometry.