1. Opener: A triangle has a 52 degree angle and a 75 degree angle. What is the measure of the other angle? Show your work and prove your answer is correct.

2. Unit 6: Geometry Identify and use the properties of angle bisectors.

3. Vocabulary Bisect: to bisect means to cut something in half, bi = 2 and ‘sect’ = to cut…remember the word ‘disect’? Perpendicular bisector: a ray or line that bisects another ray or line at a 90° angle. Angle bisector: a ray that divides an angle into 2 new angles that have the same degree measure. Objective: Identify and use the properties of angle bisectors.

4. Examples: 1) If a right angle is bisected, what are the measures of each of the new angles? 2) If an angle has been bisected and one of the new angles measures 83°, what was the measure of the original angle? 3) What angle bisector appears to bisect angle AGC? Are there any perpendicular bisectors in the figure below? What angle does ray GE appear to bisect? GAF B C D E.

5. Homework: Complete the Angle Bisector page.