Lesson_5-1_Midsegments_of_Triangles - Midsegments of...

Midsegments of Triangles
Lesson 5-1

Midsegment
A segment that joins the midpoints of two sides of a
triangle is called a midsegment.

Midsegment Properties
A midsegment of a triangle is parallel to the third side
and is half the length of the third side.
A
E D
C
B
2
mCB
mDE 

Midsegment Properties
The three midsegments of a triangle divide it into four
congruent triangles.

Example
EF is the midsegment of  BAC, determine the
length of EF
100 cm
50
2
100
2



mAC
mEF
E
F
A
B
C

Example
EF is the midsegment of  BAC, determine the
length of EF
150 cm
75
2
150
2



mAC
mEF
E
F
A
B
C

Example
Find the length of MN
250 cm
125
2
250
2



mGK
mMN
M N
G
H
K

Example
PR is the midsegment of  STU and measures
75 cm. Determine the length of SU.
mSU
mSU
mSU
mPR



150
2
75
2
75 cm
P R
S
T
U

Example
Find the length of AC
250 cm
mAC
AC


500
2
250
E F
A
B
C

Example
Find the length of AC
23 cm
E F
A
B
C
46 cm

Example
Find the length of AC
50 cm
E F
A
B
C
25 cm

Example
Find the length of AC
140 cm
E F
A
B
C
70 cm

Example