# 1.2: Triangles

## Why triangles are important

Learning about electrical theory necessitates the study of triangles. More specifically: right triangles. Before we dig too much into the right triangle, let’s go over two key points about triangles.

• All triangles have three sides. (File this fact under the “thank you Captain Obvious” category.)
• All triangles contain 180 degrees.

Figure 9. Triangle

## Different triangles

The right triangle is the most common triangle that will be used in electrical theory. It is a good idea to have a basic understanding of other triangles as well. Here are some common triangles you will come across in trigonometry.

Isosceles triangle. This triangle has two sides that are equal, and two angles that are equal.

Figure 10. Isosceles triangle

Equilateral triangle. All three sides of this triangle are equal, and all three of its angles are equal too.

Figure 11. Equilateral triangle

Similar triangles. These triangles each have different sized sides, but they share the same sized angles.

Figure 12. Similar triangles