# 1.2: Triangles

## Why triangles are important

• 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

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 Figure 13. Complementary angles.

## Ok, so what does a right triangle have to do with electrical?

vectors (more on the concept of vectors in a later chapter). These vectors each head in a different direction. In fact, they are 90 degrees to each other. When we add them, the sum of these two vectors ends up being the point between the two sides. Figure 14. Vector triangle