1. Section 4.7 Medians, Altitudes, and Perpendicular Bisectors
WARM UP

2. Measure each side of the triangle.
Activity Part 1
Draw a triangle.
Label it ∆BOY.
Measure each side of the triangle.
Find and mark the MIDPOINT of each side.

3. Activity Part 2
Draw a line connecting Point B to the MIDPOINT on the OPPOSITE SIDE.
Draw a line connecting Point O to the MIDPOINT on the OPPOSITE SIDE.
Draw a line connecting Point Y to the MIDPOINT on the OPPOSITE SIDE.

4. What is a Median?
A segment from a vertex to the midpoint of the opposite side.
Always three medians.
See the medians for a given triangle.

5. What is a Centroid? x = 6 y = 5.5 x y 3 11
Centroid: the point where all three medians meet
The medians of a triangle divide one another into ratios of 2:1.
x = 6 x y 3 11
y = 5.5

6. Activity 2 Draw a triangle. Label it ∆ WIG.
Draw a segment from W to the opposite side so that it makes a right angle with that side.

7. What is an Altitude?
The perpendicular segment from a vertex to the opposite side.
Altitudes can be drawn OUTSIDE of the triangle.

8. Orthocenter: point where three altitudes meet

9. Which line is the median?
Which line is the altitude? a b

10. What are Perpendicular Bisectors?
A line or ray that is perpendicular to the segment at its midpoint.
Does NOT have to start at a VERTEX

11. Perpendicular Bisectors
What is true of AB and AC?

12. Circumcenter: point where three perpendicular bisectors meet.

13. TOGETHER, OPEN YOUR TEXTBOOK
Page Classroom Exercises
#1-6

14. Partner Practice Page 157 # 19 (a, b, and c)
TO BE HANDED IN! Make it neat.
I only need one per group.