An angle is formed when two rays share the same endpoint, which is called the vertex of the angle. In geometric notation, the vertex is the middle letter in the name of the angle. Each angle has a degree value (°), which measures how far the ray rotates from the vertex. The degree value determines its angle type. Groupings of angles are labeled by the sum of their angles or how they are formed.
You should be familiar with these five basic angle types:
As you review angle groupings, use these tricks to help you remember the difference between complementary and supplementary angles.
All of the angles you just saw are interior angles, which occur inside a shape. Later, you will learn about exterior angles, which form outside of a shape. For now, focus on the various ways of categorizing these angles.
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