2. MIDLINE THEOREM
๏The segment that joins the
midpoints of two sides of a
triangle is parallel to the third
side and half as long.
3. A
B C
D E
In โABC, D and E are the midpoints of ๐ด๐ต
and ๐ด๐ถ respectively.
Complete the following
statements:
๏ง DE = ______
๏ง AD = ______
๏ง AE = ______
๐
๐
BC
BD
CE
4. In โABC, D and E are the midpoints of ๐ด๐ต
and ๐ต๐ถ respectively.
Fill in the blanks.
1. If DE = 12, then AC =
_____.
2. If AC =42, then DE =
_____.
3. If AD = 7, then AB = _____.
4. If BC = 36, then BE =
_____.
5. If BD = 8 and EC = 9, then
AB + BC = _____.
D
A C
B
E
24
21
14
18
34
15
5. In โMCG, A and I are the midpoints of ๐๐บ
and ๐บ๐ถ respectively.
M C
G
A I
Given: AI = 3x โ 2
CM = 9x โ 13
Question: How long is
CM?
Given: AG = 2y - 1
AM = y + 5
Question: How long is
AG?
7. In โDOG, B and E are the midpoints of
๐ท๐ and ๐ท๐บ respectively.
B
O G
D
E
If DE = 13, then
๐
๐
DG =
_____
TIME IS
UP!!!
13
8. In โDOG, B and E are the midpoints of
๐ท๐ and ๐ท๐บ respectively.
B
O G
D
E
TIME IS
UP!!!
51
If BE = 17, then BE + OG =
_____
9. In โDOG, B and E are the midpoints of
๐ท๐ and ๐ท๐บ respectively.
B
O G
D
E
Given: BE = 2x + 5
OG = 5x + 6
Question: How long is
BE?
TIME IS
UP!!!
13
10. In โDOG, B and E are the midpoints of
๐ท๐ and ๐ท๐บ respectively.
B
O G
D
E
TIME IS
UP!!!
6
If OG = 36, then
๐
๐
BE =
_____
11. In โDOG, B and E are the midpoints of
๐ท๐ and ๐ท๐บ respectively.
B
O G
D
E
Given: BD = 3a + 3
BO = 7a - 21
Question: How long is
BO?
TIME IS
UP!!!
21
12. In โDOG, B and E are the midpoints of
๐ท๐ and ๐ท๐บ respectively.
B
O G
D
E
TIME IS
UP!!!
11
If DO = 44, then
๐
๐
BD =
_____
13. In โDOG, B and E are the midpoints of
๐ท๐ and ๐ท๐บ respectively.
B
O G
D
E
Given: DE = 2y + 1
EG = 3y - 7
Question: How long is
EG?
TIME IS
UP!!!
17
14. In โDOG, B and E are the midpoints of
๐ท๐ and ๐ท๐บ respectively.
B
O G
D
E
TIME IS
UP!!!
12
If BE = 6, then GO =
_____.
15. In โDOG, B and E are the midpoints of
๐ท๐ and ๐ท๐บ respectively.
B
O G
D
E
Given: BE = 4b - 7
GO = 5b - 5
Question: How long is
GO?
TIME IS
UP!!!
10
16. In โDOG, B and E are the midpoints of
๐ท๐ and ๐ท๐บ respectively.
B
O G
D
E
TIME IS
UP!!!
45
If OB = 15, and GE = 13,
then DO + BD = _____.
17. Letโs see how well
did you understand
our lesson.
Short Quiz
18. In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
B
U V
L
E
If LE = 19, then
๐
๐
LV =
_____
1
19. B
U V
L
E
If BE = 21, then BE + UV =
_____
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
2
20. B
U V
L
E
Given: BE = 2x - 1
UV = x + 4
Question: How long is
BE?
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
3
21. B
U V
L
E
If UV = 32, then
๐
๐
BE =
_____
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
4
22. B
U V
L
E
Given: BL = 2a - 1
BU = 4a - 17
Question: How long is
BU?
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
5
23. B
U V
L
E
If LU = 56, then
๐
๐
BL =
_____
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
6
24. B
U V
L
E
Given: EL = 2y + 14
EV = 5y - 16
Question: How long is
EV?
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
7
25. B
U V
L
E
If BE = 13.8, then UV =
_____.
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
8
26. B
U V
L
E
Given: BE = 3b - 7
UV = 4b + 8
Question: How long is
UV?
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
9
27. B
U V
L
E
If BU = 17, and EV = 14,
then LU + LV = _____.
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
10
29. In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
B
U V
L
E
If LE = 19, then
๐
๐
LV =
_____
1
19
30. B
U V
L
E
If BE = 21, then BE + UV =
_____
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
2
63
31. B
U V
L
E
Given: BE = 2x - 1
UV = x + 4
Question: How long is
BE?
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
3
3
32. B
U V
L
E
If UV = 32, then
๐
๐
BE =
_____
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
4
4
33. B
U V
L
E
Given: BL = 2a - 1
BU = 4a - 17
Question: How long is
BU?
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
5
15
34. B
U V
L
E
If LU = 56, then
๐
๐
BL =
_____
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
6
14
35. B
U V
L
E
Given: EL = 2y + 14
EV = 5y - 16
Question: How long is
EV?
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
7
34
36. B
U V
L
E
If BE = 13.8, then UV =
_____.
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
8
27.6
37. B
U V
L
E
Given: BE = 3b - 7
UV = 4b + 8
Question: How long is
UV?
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
9
52
38. B
U V
L
E
If BU = 17, and EV = 14,
then LU + LV = _____.
In โLUV, B and E are the midpoints of ๐ฟ๐ and
๐ฟ๐ respectively.
10
62