# 14.3: Geometry

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This is just a general section on geometry that the engineering student should already be familiar with, but we will review a bit.

• 14.3.1: Basic Trigonometry
We have previously defined the sine and cosine of an angle in terms of the coordinates of a point on the unit circle intersected by the terminal side of the angle. In this section, we will see another way to define trigonometric functions using properties of right triangles.
• 14.3.2: Trigonometric Functions
Trigonometric functions are used to model many phenomena, including sound waves, vibrations of strings, alternating electrical current, and the motion of pendulums. In fact, almost any repetitive, or cyclical, motion can be modeled by some combination of trigonometric functions. In this section, we define the six basic trigonometric functions and look at some of the main identities involving these functions.
• 14.3.3: Trigonometric Identities
Table of trigonometric identities.

14.3: Geometry is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by LibreTexts.