1. Once you have found your seat, grab a compass and a straight edge.
Bellwork
Please find a seat and wait for your problem to find your assigned seat.
Triangle Sum Theorem!
Once you have found your seat, grab a compass and a straight edge.

2. Objective
Students will learn to create an angle bisector using a compass and a straight edge.

3. Review on Bisectors! What is an angle bisector?
An angle bisector is a ray that divides an angle into two congruent angles. K L N
LN bisects KLM.
KLN = NLM M

4. Where might you see angle bisectors?
Where else might you
find angle bisectors?

5. Can we find the missing variable?
4x+10
12x+4
4x+10=12x+4
10=8x+4
6=8x
6/8=8 or ¾=x

6. Your Turn!
2x+10
x+4
X= -6

7. Theorems Perpendicular Bisector Theorem
If a point is on the perpendicular bisector of a segment, then it is equidistant from the endpoints of the segment.
Converse of Perpendicular Bisector Theorem
If a point is equidistant from the endpoints of a segment, then it is on the perpendicular bisector of the segment.

8. Theorems Angle Bisector Theorem
If a point is on the bisector of an angle, then it is equidistant from the sides of the angle.
Converse of Angle Bisector Theorem
If a point in the interior of an angle is equidistant from the sides of the angle, then it is on the angle bisector.

9. Now lets learn how to create one.

10. Try one On a piece of paper draw an angle bisector
Show all arcs needed to create the angle bisector
Steps:
1 Draw an angle with a straight edge.
2 From the vertex, create 2 arcs ( the same distance from the vertex) on the angle.
3 From those Arcs, draw 2 arcs in the center of the angle.
4 Draw your angle bisector

11. Activity
Work in Pairs
Fold a blank sheet of paper from corner to corner.
Using those angles formed, create angle bisectors.
Label your bisectors and all of your points including the vertex point.
Show all arcs needed to create your bisectors.
You must have at least 10 bisectors.
Color in your design.

12. Homework Rewrite the 4 theorems and give an example of each
Create an angle bisector with correct labeling and appropriate arc marks. (10 points total) (can get 1 extra credit!)
Homework Rubric
Theorem 1- Written with appropriate example= 2 points,
only written or only example=1point
Theorem 2- Written with appropriate example= 2 points,
Theorem 3- Written with appropriate example= 2 points,
Theorem 4 -Written with appropriate example= 2 points,
Angle Bisector Drawing- Angle draw with all arc marks and labels=3 points
2 of the 3 above = 2 points
1 of the above = 0 points