1. Geometry 1-3 Basics of Angles Vertex- The common endpoint of an angle’s rays (plural: vertices). Interior of an angle- in between the sides of the angle. Angle- a figure formed by two rays with a common endpoint. Exterior of an angle- outside of the angle.

2. Types of Angles Acute angle: less than 90° Right angle: exactly 90° Obtuse angle: more than 90°, less than 180° Straight angle: exactly 180 °

3. Naming Angles Angles can be named three ways: 1.By its vertex R 2.By a number 1 (if it has one) 3.By a point on each ray and the vertex SRT or TRS (vertex in the middle!) S R T 1 Best, safest way!

4. More Vocab. Congruent angles- angles that have the same measure. Angle bisector- A ray that divides an angle into two congruent angles Congruent angles: ARW  LRW Angle bisector: RW A R L W 40°

5. Using a Protractor WRS =TRV = V U T R SQ W