1. Angle Bisector and Addition Postulates, Types of Angles

2.  Angle Addition Postulate : if two angles are adjacent then their sum is equal to the outer angle. A B C D ABD + DBC = ABC

3.  Acute angle : is greater than 0 degrees and less than 90 degrees

5.  Right angle is always 90 degrees.  Obtuse angle is greater than 90 degrees and less than 180 degrees. Symbol means 90 degrees

7.  Straight angle is 180 degrees.  Midpoint of a Segment : divides a segment into two congruent parts. ( two equal lengths ) A B C Point B divides AC into two congruent parts

9.  Perpendicular Lines : are lines that intersect at 90 degrees.  Symbol

10.  Perpendicular Bisector : is a line that divides a segment into two congruent parts at 90 degrees. midpoint 90 degrees Congruent Segments

11.  Angle Bisector : is a ray that divides an angle into two congruent parts. Angle bisector symbol for congruent angles The angle was divided into two equal sizes.

12.  Ray BD is the angle bisector of the angle ABC. If angle ABD is (2x – 4) degrees and angle ABC is (6x – 42)°, how any degrees is angle DBC ? A B D C Angle DBC = 30 degrees

13.  If the line PS is the perpendicular bisector of the segment CD. MD is (3x – 1)cm. and CD is (7x – 17)cm, what is the length of CM ?  Solution Solution C M D PSPS

14. Problem What are the different ways you can name this angle? D A Y DAY or YAD