Relationships within Triangles

1
Chapter 5

• Relationships within Triangles

2
Section 5.1 (p.243)

• TSWBAT use properties of midsegments to solve
  problems.
• Midsegment of a triangle a segment connecting
  the midpoints of two sides.

A
D
G
T
O
C
3
Triangle Midsegment Theorem

• If a segment joins the midpoints of two sides of
  a triangle then the segment is parallel to the
  third side, and is half its length.

I
Ex 1 If ML 7, Find SE ________
L
M
S
E
4
Example 2

• If a segment joins the midpoints of two sides of
  a triangle then the segment is parallel to the
  third side, and is half its length.

I
EX2 If SE 13, Find ML _______
L
M
S
E
5
Example 3

• If a segment joins the midpoints of two sides of
  a triangle then the segment is parallel to the
  third side, and is half its length.

I
EX3 If LE 35, ML 40 and IM 10 Find
SE __________ Find SM _________ Find LI
__________
L
M
S
E
6
Angles too, not just sides
T
Given Angle P is 65 degrees Find Measure of
Angle A______ Measure of Angle K______ Measure
of Angle R______
A
65
R
P
K
7
More Angles ?
O
E
M
G
T
Y
Given Angle G measures 60 degrees, Angle O
measures 70 degrees, and Angle T measures 50
degrees Find the following Angle
measures OEM TMY MEY OME GEY EYM
8
More than one midsegment drawn
A
Given Angle F is 70 degrees Angle BCD is 140
degrees BC 10 inches AD 36 inches
C
B
D
F
E
Find the following Measure angle
ABC__________ measure Angle D____________ Measu
re angle CBE__________ measure Angle
A____________ Length of BE _______________ Len
gth of FE _______________
9
C
B
D
A
F
E
TRY If FD 3x 1, and AC 5x 7, find the
value of x__________
10
C
B
D
A
F
E
TRY If BF 2x 6, CE 5x 9, Find the value
of x ___________
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Challenge?
C
B
D
A
F
E
EX If BD x 85, CD x 50, BA x, and AE
3x 46 Find AC ____________ Find DE
____________ Find AE ____________ Find the
Perimeter of Triangle ACE and Triangle FBD
12
Assignment

• Classwork P246 1-20, 27 33
• Homework WBp 54