1. 1.4 Measure and Classify Angles

2. Definitions Angle – consists of two different rays with the same endpoint. B C vertex The rays are the sides of the angle. The endpoint is the vertex of the angle. A sides This angle can be named BAC or CAB or A.

3. Classifying Angles Acute Angle: less than 90º Right Angle: equals 90º Obtuse Angle: more than 90º Straight Angle: equals 180º A B C D

4. Angle Addition Postulate If P is in the interior of RST, then R S T P m RST = m RSP + m PST

5. Congruent Angles Two angles are congruent if they have the same measure. A B 24º so A = B ~ m A= m B