1. Angles of Triangles
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Look at the interior angles of the large triangle.
151^(∘)
We are given the measures of two interior angles of a triangle.
We are asked to find the measure of angle 2. To do so, notice that ∠ 5 and ∠ 2 form a linear pair.
Pairs of angles can be classified in different ways depending on how their measures relate. Let's see this classification in the following table!
| Pair of Angles | |
|---|---|
| Complementary Angles | Two angles whose measures add up to 90^(∘) or π2 radians. |
| Supplementary Angles | Two angles whose measures add up to 180^(∘) or π radians. They are also called linear pairs because they form a straight angle. |
| Vertical Angles | Vertical angles are formed on opposite sides of the point of intersection. |
More information about theorems related to angles can be found on the following pages.