1. LESSON 5-3
MEDIANS, ALTITUDES & ANGLE
BISECTORS OF TRIANGLES
OBJECTIVE:
To define and use medians, altitudes
and angle bisectors of triangles

2. DEFINITIONS: is a segment whose endpoints are
A median of a triangle
is a segment whose endpoints are
a vertex of the triangle and the
midpoint of the opposite side.

3. A B C
 EX. #1
Sketch, label and mark
3 medians for ABC. E F D

4. An altitude of a triangle
is a segment from a vertex of the triangle
and perpendicular to the line containing
the opposite side.

5. EX. #2
 Sketch, label & mark
altitudes for each of the
3 triangles. A D B E C F T Y Q R S X U T V Z

6. An angle bisector in a triangle
is a segment that bisects one of the angles
of a triangle and whose endpoints are
on the triangle.

7. C
EX. #3
 Sketch, label and mark
angle bisectors for CAR. B O X A R

8. Complete the following proof: Given: AB  CB BD is a median of ABC
Given: AB  CB
BD is a median of ABC
 Prove: ABD   CBD D A B C

9. 1. BD is a med of ABC 1. GIVEN 2. D is the midpt of AC
STATEMENTS REASONS
1. BD is a med of ABC GIVEN
2. D is the midpt of AC
2. Def. of med.
3. AD  CD
3. Def. of midp.
4. AB  CB
4. GIVEN

10. 5. BD  BD 5. Ref. Prop  6. SSS Post. 6. ABD  CBD 7. CPCTC

11. ASSIGNMENT:
Lesson 5.3 Worksheet