1. 4/26 Half Day

2. Do Now 4/26 EQ: What is the triangle proportionality theorem?
1. What is the length of side BC?
2. If you could travel anywhere in the world, where would you go and why?
EQ: What is the triangle proportionality theorem?

3. Agenda Do Now Good Things! Unit 4 Review Notes: Practice Problems
Triangle Proportionality Theorem
Triangle Bisector Theorem
Practice Problems

4. Good things

5. Triangle proportionality theorem
In this figure
*the arrows in the middle tell us that these lines are parallel
According to this theorem,
Left Short / Left Long = Right Short / Right Long

6. Triangle Proportionality theorem
If a line parallel to one side of a triangle intersects the other two sides of the triangle, then the parallel line divides the other two sides proportionally
How is this different from the midsegment theorem?

7. Triangle Proportionality Theorem
1. Are lines DE & AC parallel?
2. Write a proportion to find the missing side

8. Working Backwards
If the parts are proportional, this means that the line crossing the triangle MUST be parallel.
Is DE parallel to AC???
Are these ratios equal? NO
Line DE is not parallel to AC because of the Triangle Proportionality Theorem

9. Partner Practice
Find the length of CD
Is AB parallel to EC?

10. Triangle Angle Bisector Theorem
A bisector is a line that cuts something in half
If an angle of a triangle is bisected (cut in half), the bisector divides the opposite side of the triangle into two segments that are proportional to the other two sides of the triangle
Bisector
bottom parts of both triangles
hypotenuse of both triangles

11. Group Practice
Find the length of BD
Find the lengths of CD & CB

12. Practice Problems
Online worksheet