This document provides instruction on trigonometric ratios and their uses in solving problems involving right triangles. It defines the three basic trigonometric functions - sine, cosine, and tangent - in terms of ratios of sides of a right triangle with a given angle of perspective. Examples are given of calculating trigonometric ratios and using them to find missing side lengths or angle measures. The document also distinguishes between angles of elevation and depression and provides examples of application problems involving each.