2. Angles Measures Angles Measures Objective: Identify angles & parts of angles Identify angles & parts of angles Use the angle addition postulate to find the measures of angles Use the angle addition postulate to find the measures of angles

3. RAYS A ray is a segment that is extended indefinitely in one direction. A ray is a segment that is extended indefinitely in one direction. Rays have only one endpoint and that point is always named first when naming the ray. Rays have only one endpoint and that point is always named first when naming the ray. Ray PQ, written PQ, consists of the points on PQ and all points S on PQ such that Q is between P & S. Ray PQ, written PQ, consists of the points on PQ and all points S on PQ such that Q is between P & S. PQ S

4. Angles It is formed by 2 non-collinear rays called the sides of the angle and common end point called vertex. It is formed by 2 non-collinear rays called the sides of the angle and common end point called vertex. Z X Y 1 The sides are: YX and YZ and the vertex Y How we name the angle? YXYZ ZYX 1

5. Angles SP Q R 1 2 3 What number names ? QSP 2 What is the vertex of ?What are the sides of ? 1

6. Angles A B C D Interior Exterior

7. Angles Measure of an angle. To measure an angle we need to use the protractor How we use the protractor

8. Angles To measure an angle place the center of the protractor over the vertex of the angle. Align the mark labeled 0 on either side of the scale with one side of the angle y z x

9. Angles Find the degree measure of each numbered angle. 2 1 3 4 m = ? 1 2 3 4 30 95 18 37

10. Angles R S P Q If R is in the interior of, then m + m = m If m + m = m then R is in the interior of. PQSPQRRQS PQS PQRRQS PQS