Triangles Chapter Problems
Classify the Triangles by Sides or Angles
Class Work
In problems #1-10, choose the most appropriate description for the given triangle. (Equilateral,
Scalene, Isosceles, Obtuse, Acute, Right, Equiangular)
1. Side lengths: 3 cm, 4 cm, 5 cm
2. Side lengths: 3 cm, 3 cm, 4 cm
3. Side lengths: 2 cm, 3 cm, 2 cm
4. Side lengths: 5 cm, 5 cm, 5 cm
5. Side lengths: 2 cm. 3 cm, 4 cm
6. Angle Measures: 30°, 60°, 90°
7. Angle Measures: 60°, 60°, 60°
8. Angle Measures: 92°, 37°, 51°
9. Angle Measures: 88°, 67°, 25°
10. Angle measures: 37°, 39°, 104°
Complete the statement using ALWAYS, SOMETIMES, and NEVER.
11. An isosceles triangle is ___________ a scalene triangle.
12. An equilateral triangle is __________ an isosceles triangle.
13. An isosceles triangle is ___________ an equilateral triangle.
14. An acute triangle is ___________ an equiangular triangle.
15. An isosceles triangle is __________ a right triangle.
For #16-20, classify the triangles by Sides & Angles
17.
16.
18.
64°
37°
22°
115°
58°
58°
106°
43°
37°
19.
20.
135°
Geometry: Triangles
~1~
NJCTL.org
Classify the Triangles by Sides or Angles
Homework
In problems #21-30, choose the most appropriate description for the given triangle.
(Equilateral, Scalene, Isosceles, Obtuse, Acute, Right, Equiangular)
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
Side lengths: 5 cm, 6 cm, 7 cm
Side lengths: 2 cm, 2 cm, 3 cm
Side lengths: 3 cm, 3 cm, 3 cm
Side lengths: 3 cm, 4 cm, 4 cm
Side lengths: 4 cm, 3 cm, 2 cm
Angle Measures: 60°, 60°, 60°
Angle Measures: 60°, 30°, 90°
Angle Measures: 33°, 52°, 95°
Angle Measures: 37°, 43°, 100°
Angle measures: 25°, 67°, 88°
Complete the statement using ALWAYS, SOMETIMES, and NEVER.
31. A scalene triangle is ___________ an equilateral triangle.
32. An equilateral triangle is __________ an obtuse triangle.
33. An isosceles triangle is ___________ an acute triangle.
34. An equiangular triangle is ___________ a right triangle.
35. A right triangle is __________ an isosceles triangle.
For #36-40, classify the triangles by Sides & Angles
38.
37.
36.
27°
36°
47°
108°
106°
36°
40.
39.
51°
46°
78°
46°
51°
Geometry: Triangles
~2~
NJCTL.org
Triangle Sum & Exterior Angle Theorems
Class Work
In the given triangles, solve for the missing variable(s).
Geometry: Triangles
~3~
NJCTL.org
Triangle Sum & Exterior Angle Theorems
Homework
In the given triangles, solve for the missing variable(s).
Geometry: Triangles
~4~
NJCTL.org
PARCC type question
66. Proof of Triangle Sum Theorem: Complete the proof by filling in the missing reasons
with the “reasons bank” to the right. Some reasons may be used more than once, and some
may not be used at all.
D
Given: j || k, ∠𝐷𝐵𝐸 is a straight angle
Prove: 𝑚∠1 + 𝑚∠4 + 𝑚∠7 = 180°
E
B
3 4
2 1
C
Statements
1. j || k
∠𝐷𝐵𝐸 is a straight angle
2. 𝑚∠𝐷𝐵𝐸 = 180°
3. 𝑚∠3 + 𝑚∠4 + 𝑚∠5 = 𝑚∠𝐷𝐵𝐸
4. 𝑚∠3 + 𝑚∠4 + 𝑚∠5 = 180°
5. ∠3 ≅ ∠1, ∠5 ≅ ∠7
6. 𝑚∠3 = 𝑚∠1, 𝑚∠5 = 𝑚∠7
7. 𝑚∠1 + 𝑚∠4 + 𝑚∠7 = 180°
k
5
7
Reasons
1.
6
A
Reasons Bank
a) Angle Addition Postulate
b) Substitution Property of Equality
c) If 2 parallel lines are cut by a
transversal, then the alternate interior
angles are congruent.
d) If 2 parallel lines are cut by a
transversal, then the corresponding
angles are congruent.
e) Given
f) Definition of congruent angles.
g) Definition of a straight angle.
2.
3.
4.
5.
6.
7.
Inequalities in Triangles
Class work
For each triangle list the sides from greatest to smallest #67-69.
67.
68.
69.
B
H
D
30°
A
C
65°
F
24°
112°
E
G
76°
I
75°
For each triangle list the angles in order from greatest to smallest #70-72.
70.
71.
72.
L M
5.7
O
4
Geometry: Triangles
Q
6.75
2.5
K
J
62
43
j
3.8
60
P
N
~5~
5.5
R
NJCTL.org
Will the three lengths given make a triangle?
73. 2, 3, and 4
74. 1, 3, and 4
75. 5, 6, and 7
76. 16, 8, and 7
77. 20, 10, and 10
78. 8x, 7x, and 14x
Given the lengths of two sides of a triangle, what lengths could the third side, x, have?
79. 12 and 14
80. 15 and 6
81. 22 and 22
82. 9 and 12
83. 8y and 10y
Inequalities in Triangles
Homework
For each triangle list the sides from greatest to smallest #84-86.
84.
85.
86.
E
B
H
57°
41°
95°
C D
A
F
63°
80°
G
18°
I
For each triangle list the angles in order from greatest to smallest #87-89.
87.
88.
89.
M
K
H
18
N
10
5
7
G
7
Geometry: Triangles
8
I J
L
27
33
11
O
~6~
NJCTL.org
List the sides in order from shortest to longest #90-91.
90.
91.
H
T
75° 40°
80°
S
40° 80°
V
G
75°
70°
110° 40°
U
F
I
60°
J
Will the three lengths given make a triangle?
92. 21, 34, and 49
93. 11, 31, and 44
94. 8, 6, and 5
95. 12, 5, and 7
96. 20, 30, and 11
97. 9x, 17x, and 26x
Given the lengths of two sides of a triangle, what lengths could the third side, x, have?
98. 10 and 21
99. 19 and 8
100. 30 and 30
101. 5 and 15
102. 4y and 14y
Similar Triangles
Class work
103. Determine if the triangles are similar. If so, write a similarity statement & state the
similarity postulate or theorem.
a.
A
D
E
F
b.
C
B
c.
G
K
J
M
P
R
H
L
Geometry: Triangles
N
~7~
Q
NJCTL.org
PARCC type questions: Complete the proof by filling in the missing reasons with the
“reasons bank” to the right. Some reasons may not be used at all.
104. Given: DH || FG
Prove: ∆𝐷𝐸𝐻~∆𝐺𝐸𝐹
Reasons Bank
F
D
a) If 2 parallel lines are cut by a
transversal, then the alternate interior
angles are congruent.
b) If 2 parallel lines are cut by a
transversal, then the corresponding
angles are congruent.
c) Given
d) Vertical angles are congruent
e) AA~
f) SAS~
g) SSS~
E
G
H
Statements
1. DH || FG
2. ∠𝐷 ≅ ∠𝐺
3. ∠𝐷𝐸𝐻 ≅ ∠𝐺𝐸𝐹
4. ∆𝐷𝐸𝐻~∆𝐺𝐸𝐹
Reasons
1.
2.
3.
4.
105. Given: ÐR @ ÐA , PR = 9 , QR = 7.2 , AB = 4.8 , and AC = 6
Prove: ∆𝑄𝑃𝑅~∆𝐵𝐶𝐴
Reasons Bank
Statements
1. ÐR @ ÐA , PR = 9 , QR = 7.2 ,
AB = 4.8 , and AC = 6
2.
𝑃𝑅
𝐶𝐴
𝑃𝑅
9
3 𝑄𝑅
7.2
3
= 6 = 2 , 𝐵𝐴 = 4.8 = 2
𝑄𝑅
Reasons
1.
2.
3.
3. 𝐶𝐴 = 𝐵𝐴
4. ∆𝑄𝑃𝑅~∆𝐵𝐶𝐴
106.
a) If the scale factors are the same, then the
sides are proportional.
b) Given
c) AA~
d) Calculating the scale factor between the
sides of the triangles.
e) SAS~
f) SSS~
4.
Given: ÐA @ ÐD , ÐB @ ÐE
Prove: ∆𝐴𝐵𝐶~∆𝐷𝐸𝐹
E
Reasons Bank
B
A
C
Statements
1. ÐA @ ÐD , ÐB @ ÐE
2. ∆𝐴𝐵𝐶~∆𝐷𝐸𝐹
Geometry: Triangles
F
D
a)
b)
c)
d)
AA~
SAS~
SSS~
Given
Reasons
1.
2.
~8~
NJCTL.org
107.
AB BC CA


DE EF FD
Prove: ∆𝐴𝐵𝐶~∆𝐷𝐸𝐹
Given:
Reasons Bank
a)
b)
c)
d)
E
B
A
C
F
D
Statements
AB BC CA


1.
DE EF FD
2. ∆𝐴𝐵𝐶~∆𝐷𝐸𝐹
Reasons
1.
2.
In problems 108-111, determine if DE || BC .
108.
110.
PARCC type questions:
Solve for y.
112.
Geometry: Triangles
AA~
SAS~
SSS~
Given
109.
111.
113.
~9~
NJCTL.org
114.
115.
116.
117.
118.
119.
Geometry: Triangles
~10~
NJCTL.org
PARCC type question: Complete the proof by filling in the missing reasons with the “reasons
bank” to the right. Some reasons may not be used at all.
120. Prove the Side Splitter Theorem
Reasons Bank
Given BD ║ AE
𝐵𝐴
𝐷𝐸
Prove 𝐶𝐵 = 𝐶𝐷
a) If 2 parallel lines are cut by a
transversal, then the alternate interior
angles are congruent.
b) If 2 parallel lines are cut by a
transversal, then the corresponding
angles are congruent.
c) Given
d) Reflexive Property of Congruence
e) AA~
f) SAS~
g) If two triangles are similar, then their
corresponding sides are proportional.
h) SSS~
i) Substitution Property of Equality
j) Subtraction Property of Equality
k) Addition Property of Equality
l) Segment Addition Postulate
m) Addition Property of Fractions
2
1
2+1
3
(𝑒. 𝑔. 5 + 5 = 5 = 5)
n) Simplifying the Equation
C
B
D
A
E
Statements
1. BD ║ AE
2. ∠𝐶 ≅ ∠𝐶
3. ∠𝐶𝐵𝐷 ≅ ∠𝐶𝐴𝐸
4. ∆𝐶𝐵𝐷~∆𝐶𝐴𝐸
𝐶𝐴
𝐶𝐸
5.
=
𝐶𝐵
𝐶𝐷
6. CA = CB + BA
CE = CD + DE
𝐶𝐵+𝐵𝐴
𝐶𝐷+𝐷𝐸
7. 𝐶𝐵 = 𝐶𝐷
8.
𝐶𝐵
𝐶𝐵
Reasons
1.
2.
3.
4.
𝐵𝐴
𝐶𝐷
5.
6.
7.
𝐷𝐸
+ 𝐶𝐵 = 𝐶𝐷 + 𝐶𝐷
𝐵𝐴
𝐷𝐸
9.
9. 1 + 𝐶𝐵 = 1 + 𝐶𝐷
10.
𝐵𝐴
𝐶𝐵
=
8.
𝐷𝐸
𝐶𝐷
10.
Similar Triangles
Homework
121. Determine if the triangles are similar. If so, write a similarity statement & state the
N
similarity postulate or theorem.
a.
b.
c.
A
L
E
H
G
K
B
D
Geometry: Triangles
C
F
J
~11~
M
P
NJCTL.org
Q
PARCC type questions: Complete the proof by filling in the missing reasons with the “reasons
bank” to the right. Some reasons may not be used at all.
122. Given: BD || AE
Reasons Bank
Prove: ∆𝐴𝐶𝐸~∆𝐵𝐶𝐷
a) If 2 parallel lines are cut by a
transversal, then the alternate interior
angles are congruent.
b) If 2 parallel lines are cut by a
transversal, then the corresponding
angles are congruent.
Statements
Reasons
c) Given
1.
1. BD ║ AE
d) Reflexive Property of Congruence
2.
2. ∠𝐶 ≅ ∠𝐶
e) AA~
3.
3. ∠𝐶𝐷𝐵 ≅ ∠𝐶𝐸𝐴
f) SAS~
4.
4. ∆𝐴𝐶𝐸~∆𝐵𝐶𝐷
g) SSS~
123. Given: mÐP = 48°, mÐQ = 55° , mÐB = 55° , mÐC = 77°
Prove: ∆𝑃𝑄𝑅~∆𝐴𝐵𝐶
Reasons Bank
Statements
1. mÐP = 48°, mÐQ = 55° ,
mÐB = 55° , mÐC = 77°
2. 𝑚∠𝑅 = 77°
3. ∠𝑄 ≅ ∠𝐵, ∠𝑅 ≅ ∠𝐶
4. ∆𝑃𝑄𝑅~∆𝐴𝐵𝐶
a)
b)
c)
d)
e)
f)
Reasons
1.
Triangle Sum Theorem
Given
AA~
SAS~
Definition of congruent angles
SSS~
2.
3.
4.
Reasons Bank
AB CA

, ÐA @ ÐD
DE FD
Prove: ∆𝐴𝐵𝐶~∆𝐷𝐸𝐹
124. Given:
a)
b)
c)
d)
E
AA~
SAS~
SSS~
Given
B
A
C
Statements
AB CA

1.
, ÐA @ ÐD
DE FD
2. ∆𝐴𝐵𝐶~∆𝐷𝐸𝐹
Geometry: Triangles
F
D
Reasons
1.
2.
~12~
NJCTL.org
In problems 125-128, determine if DE || BC .
125.
127.
PARCC type questions:
Solve for y.
129.
131.
Geometry: Triangles
126.
128.
130.
132.
~13~
NJCTL.org
133.
134.
135.
136.
PARCC type question:
137. Prove the Converse to the Side Splitter Theorem: Complete the proof by filling in the
missing reasons with the “reasons bank” to the right. Some reasons may not be used at all.
𝐵𝐴
𝐷𝐸
Given 𝐶𝐵 = 𝐶𝐷
C
Reasons Bank
Prove BD ║ AE
B
A
Statements
𝐵𝐴
𝐷𝐸
1. 𝐶𝐵 = 𝐶𝐷
𝐵𝐴
𝐷𝐸
D
E
Reasons
1.
2. 1 + 𝐶𝐵 = 1 + 𝐶𝐷
2.
3.
3.
𝐶𝐵
𝐵𝐴
𝐶𝐷
𝐷𝐸
+ 𝐶𝐵 = 𝐶𝐷 + 𝐶𝐷
𝐶𝐵
𝐶𝐵+𝐵𝐴
𝐶𝐷+𝐷𝐸
=
𝐶𝐵
𝐶𝐷
4.
5. CA = CB + BA
CE = CD + DE
𝐶𝐴
𝐶𝐸
6. 𝐶𝐵 = 𝐶𝐷
4.
7. ∠𝐶 ≅ ∠𝐶
8. ∆𝐶𝐵𝐷~∆𝐶𝐴𝐸
9. ∠𝐶𝐵𝐷 ≅ ∠𝐶𝐴𝐸
10. BD ║ AE
7.
8.
9.
10.
Geometry: Triangles
a) If 2 lines are cut by a transversal and the
alternate interior angles are congruent,
then the lines are parallel.
b) If 2 lines are cut by a transversal and the
corresponding angles are congruent,
then the lines are parallel.
c) Given
d) Reflexive Property of Congruence
e) AA~
f) SAS~
g) SSS~
h) If two triangles are similar, then the
corresponding angles are congruent.
i) Substitution Property of Equality
j) Subtraction Property of Equality
k) Addition Property of Equality
l) Segment Addition Postulate
m) Addition Property of Fractions
2
1
2+1
3
(𝑒. 𝑔. 5 + 5 = 5 = 5)
n) Simplifying the Equation
5.
6.
~14~
NJCTL.org
Applications
Class work
138. You want to know the approximate height of your school building. You place a mirror
on the ground and stand where you can see the top of the building in the mirror. How
tall is your school? The mirror is 30 feet from the base of the school. You are 36
inches from the mirror and your eyes are 5 feet above the ground.
Round your answer to the nearest whole number.
139. You want to know the approximate height of a very tall pine tree. You place a mirror
on the ground and stand where you can see the top of the tree in the mirror. How tall
is the tree? The mirror is 24 feet from the base of the tree. You are 24 inches from the
mirror and your eyes are 6 feet above the ground. Round your answer to the nearest
tenth.
140. To find the distance d across a lake, you locate the points as shown. Find the value of
d. Round your answer to the nearest tenth.
120 ft
d
15 ft
20 ft
Applications
Homework
141. You want to know the approximate height of your house. You place a mirror on the
ground and stand where you can see the top of your house in the mirror. How tall is
your house? The mirror is 25 feet from the base of your house. You are 60 inches
from the mirror and your eyes are 5 feet 6 inches above the ground. Round your
answer to the nearest tenth.
142. You want to know the approximate height of a tall oak tree. You place a mirror on the
ground and stand where you can see the top of the tree in the mirror. How tall is the
tree? The mirror is 24 feet from the base of the tree. You are 36 inches from the mirror
and your eyes are 5 feet above the ground. Round your answer to the nearest tenth.
Geometry: Triangles
~15~
NJCTL.org
143. To find the distance d across a lake, you locate the points as shown. Find the value of
d. Round your answer to the nearest tenth.
28 ft
15 ft
56 ft
d
Geometry: Triangles
~16~
NJCTL.org
Triangles Review
Multiple Choice
1. Identify the triangles by sides and angles
a. scalene, acute
b. isosceles, obtuse
c. scalene, obtuse
d. equilateral, equiangular
2. Angle measures of a triangle are given, find the value of x.
a. 24
A triangle’s angles are:
b. 28
m∠𝐴 = 2x - 1
c. 32
m∠𝐵 = x + 9
d. 30
m∠𝐶 = 3x + 4
3. Classify the triangle by sides and angles.
a. scalene, obtuse
b. isosceles, acute
c. scalene, acute
d. isosceles, obtuse
8
12
10
4. Using the figure at right, list the segments from least to greatest.
̅̅̅̅ , 𝐴𝐶
̅̅̅̅ , 𝐵𝐶
̅̅̅̅ , 𝐴𝐷
̅̅̅̅, 𝐷𝐶
̅̅̅̅
a. 𝐵𝐶
̅̅̅̅ , ̅̅̅̅
b. ̅̅̅̅
𝐴𝐵 , 𝐵𝐶
𝐴𝐶 , ̅̅̅̅
𝐴𝐷 , ̅̅̅̅
𝐷𝐶
̅̅̅̅
̅̅̅̅
̅̅̅̅
̅̅̅̅
̅̅̅̅
c. 𝐴𝐷, 𝐷𝐶 , 𝐴𝐶 , 𝐴𝐵 , 𝐵𝐶
d. cannot be determined
5. Use the diagram to find the value of x.
a. 130
b. 125
c. 120
d. 110
6. Which of the following values cannot be the third side of a triangle if two of the sides are 14
and 20?
a. 18
b. 20
c. 32.5
d. 34
Geometry: Triangles
~17~
NJCTL.org
7. Decide whether the triangles are similar. If so, write a similarity statement.
a.
b.
c.
d.
Yes, DABC : DDEF
Yes, DABC : DDFE
Yes, DABC : DFDE
The triangles are not similar
8. Determine if the triangles are similar. If so, state the similarity postulate or theorem.
a.
b.
c.
d.
Yes, by AA~
Yes, by SSS~
Yes, by SAS ~
The triangles are not similar
9. Determine if the triangles are similar. If so, state the similarity postulate or theorem.
B
a.
b.
c.
d.
C
A
Yes, by AA~
Yes, by SSS~
Yes, by SAS ~
The triangles are not similar
D
E
10. Solve for y
a.
b.
c.
d.
8
4.5
6
12
Geometry: Triangles
~18~
NJCTL.org
11. Solve for x
F
E
6
10
G
8
D
a.
b.
c.
d.
H
x
4
4.8
10
12.8
Short Constructed Response – Write the correct answer for each question.
No partial credit will be given.
12. Find the values of x and z.
x
2x-10
40
z
13. ∆𝐽𝐾𝐿~∆𝑁𝑃𝑀. Find the values if x & y
K
P
12
9
J
L
x
13.5
15
M
Geometry: Triangles
y
~19~
N
NJCTL.org
14. To find the distance d across a stream, you locate the points as shown. Find the value
of d.
200 ft
d
21 ft
28 ft
Extended Constructed Response – Write the correct answer for each question.
Partial credit will be given.
15. Complete the proof by filling in the missing reasons with the “reasons bank” to the right.
Some reasons may not be used at all.
Given BD ║ AE
Reasons Bank
Prove ∆𝐵𝐶𝐷~∆𝐴𝐶𝐸
a) If 2 parallel lines are cut by a
C
transversal, then the alternate interior
angles are congruent.
b) If 2 parallel lines are cut by a
transversal, then the corresponding
angles are congruent.
c)
Reflexive Property of Congruence
B
D
d) AA~
e) SAS~
f) Given
A
E
g) SSS~
Statements
Reasons
1.
1. BD ║ AE
2.
2. ∠𝐶 ≅ ∠𝐶
3.
3. ∠𝐶𝐵𝐷 ≅ ∠𝐶𝐴𝐸
4.
4. ∆𝐵𝐶𝐷~∆𝐴𝐶𝐸
Geometry: Triangles
~20~
NJCTL.org
Answers
1. Scalene
2. Isosceles
3. Isosceles
4. Equilateral and isosceles
5. Scalene
6. Right
7. Equiangular & acute
8. Obtuse
9. Acute
10. Obtuse
11. Never
12. Always
13. Sometimes
14. Sometimes
15. Sometimes
16. Sides: Isosceles, Angles: Acute
17. Sides: Scalene, Angles: Obtuse
18. Sides: Isosceles, Angles: Obtuse
19. Sides: Scalene, Angles: Right
20. Sides: Isosceles, Angles: Obtuse
21. Scalene
22. Isosceles
23. Equilateral and isosceles
24. Isosceles
25. Scalene
26. Equiangular & acute
27. Right
28. Obtuse
29. Obtuse
30. Acute
31. Never
32. Never
33. Sometimes
34. Never
35. Sometimes
36. Sides: Scalene, Angles: Right
37. Sides: Scalene, Angles: Obtuse
38. Sides: Isosceles, Angles: Obtuse
39. Sides: Isosceles, Angles: Acute
40. Sides: Isosceles, Angles: Acute
41. X=58°
42. X=33°
43. X=23°
44. X=30°
45. X=79°, z=144°, y=55°
46. X=12
Geometry: Triangles
47. X=27
48. X=76°, y=104°, z=55°
49. j = 47, k = 180, m = 155, n = 25,
p = 94, q = 61
50. r = 35, t = 145, u = 35, v = 90,
w = 125
51. a = 54, b = 36, c = 36, d = 116,
e = 152, f = 28, g = 98, h = 54
52. j = 128, k = 52, m = 52, n = 31,
p = 149, q = 31, r = 49, t = 131
53. X=61°
54. X=31
55. X=37
56. X=27
57. X=32
58. X=96°, z=151°, y=68
59. X=66°, z=88°, y=79°
60. Z=90°, y=43°, x=71°
61. X=95°, y=51°, z=39°
62. a = 127, b = 90, c = 143, d = 37,
e = 74, f = 111
63. g = 49, h = 117, j = 49, k = 76,
m = 55
64. a = 143, b = 37, c = 37, d = 121,
e = 158, f = 22, g = 108, h = 50
65. r = 90, t = 38, u = 38, v = 34,
w = 146, x = 34, y = 30, z = 150
66.
Statements
Reasons
1. j || k
1. e
∠𝐷𝐵𝐸 is a straight
angle
2. g
2. 𝑚∠𝐷𝐵𝐸 = 180°
3. a
3. 𝑚∠3 + 𝑚∠4 +
𝑚∠5 = 𝑚∠𝐷𝐵𝐸
4. b
4. 𝑚∠3 + 𝑚∠4 +
𝑚∠5 = 180°
5. c
5. ∠3 ≅ ∠1, ∠5 ≅ ∠7
6. f
6. 𝑚∠3 = 𝑚∠1, 𝑚∠5 =
𝑚∠7
7.b
7. 𝑚∠1 + 𝑚∠4 +
𝑚∠7 = 180°
AC, BC, AB
68. DF, EF, DE
69. GI, HI, HG
67.
~21~
NJCTL.org
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
81.
82.
83.
84.
<K, <L, <J
<N, <M, <O
<P, <Q, <R
yes
no
yes
no
no
yes
2 < x < 26
9 < x < 21
0 < x < 44
3 < x < 21
2y < x < 18y
105.
Statements
1. ÐR @ ÐA , PR = 9 ,
QR = 7.2 , AB = 4.8 , and
AC = 6
2.
𝐶𝐴
𝑃𝑅
9
3 𝑄𝑅
7.2
3
= 6 = 2 , 𝐵𝐴 = 4.8 = 2
𝑄𝑅
106.
Statements
1. ÐA @ ÐD , ÐB @ ÐE
2. DABC : DDEF
107.
Statements
AB BC CA


1.
DE EF FD
2. DABC : DDEF
87. <H @ <I, <G
88. <K, <J, <L
89. <N, <M, <O
90. UV,TV,UT ,ST ,SU
2. d
3. a
4. e
Reasons
1. d
2. a
Reasons
1. d
2. c
108. yes
109. no
110. no
111. yes
112. 12
113. 11.36
52
114. 15 = 3.46̅
115. 11.2
116. 4.5
117. 9.2
118. 18
119. 5
91. FJ,GF,GJ,GH, HJ, HI, JI
92. yes
93. no
94. yes
95. no
96. yes
97. no
98. 11< x < 31
99. 11 < x < 27
100.
0 < x < 60
101.
10 < x < 20
102.
10y < x < 18y
103.
a. not similar
b. yes ∆𝐺𝐻𝐽~∆𝐿𝐽𝐾 by SAS
c. not similar
104.
Statements
Reasons
1. c
1. DH || FG
120.
Statements
1. BD ║ AE
2. ∠𝐶 ≅ ∠𝐶
3. ∠𝐶𝐵𝐷 ≅ ∠𝐶𝐴𝐸
4. ∆𝐶𝐵𝐷~∆𝐶𝐴𝐸
2. a
3. d
4. e
𝐶𝐴
𝐶𝐸
5. 𝐶𝐵 = 𝐶𝐷
6. CA = CB + BA
CE = CD + DE
𝐶𝐵+𝐵𝐴
𝐶𝐷+𝐷𝐸
7.
=
8.
Geometry: Triangles
𝑃𝑅
3. 𝐶𝐴 = 𝐵𝐴
4. DQPR : DBCA
BC, AB, AC
85. EF, DE, DF
86. GI, HI,GH
2. ∠𝐷 ≅ ∠𝐺
3. ∠𝐷𝐸𝐻 ≅ ∠𝐺𝐸𝐹
4. DDEH : DGEF
Reasons
1. b
~22~
𝐶𝐵
𝐶𝐵
𝐵𝐴
+ 𝐶𝐵
𝐶𝐵
=
𝐶𝐷
𝐶𝐷
𝐷𝐸
+ 𝐶𝐷
𝐶𝐷
Reasons
1. c
2. d
3. b
4. e
5. g
6. l
7. i
8. m
NJCTL.org
𝐵𝐴
𝐷𝐸
9. 1 + 𝐶𝐵 = 1 + 𝐶𝐷
10.
𝐵𝐴
𝐶𝐵
=
𝐷𝐸
𝐶𝐷
9. n
127. no
128. no
129. 10
130. 11.25
131. 10
132. 6
133. 4.5
134. 11.4
135. 8
136. 16.2
10. j
121. a. yes, ∆𝐴𝐵𝐷~∆𝐴𝐶𝐷 by AA~ or
SAS~
b. not similar
c. yes, ∆𝐾𝐿𝑀~∆𝑄𝑁𝑃 by SSS~
122.
Statements
1. BD ║ AE
2. ∠𝐶 ≅ ∠𝐶
3. ∠𝐶𝐷𝐵 ≅ ∠𝐶𝐸𝐴
4. ∆𝐶𝐵𝐷 ≅ ∆𝐶𝐴𝐸
123.
Statements
1. mÐP = 48°,
mÐQ = 55° , mÐB = 55° ,
mÐC = 77°
2. 𝑚∠𝑅 = 77°
3. ∠𝑄 ≅ ∠𝐵, ∠𝑅 ≅ ∠𝐶
4. DPQR : DABC
124.
Statements
AB CA

1.
, ÐA @ ÐD
DE FD
2. DABC : DDEF
Reasons
1. c
2. d
3. b
4. e
137.
Statements
𝐵𝐴
𝐷𝐸
1. 𝐶𝐵 = 𝐶𝐷
𝐵𝐴
Reasons
1. b
2. a
3. e
4. c
Reasons
1. d
125. yes
126. yes
𝐷𝐸
2. 1 + 𝐶𝐵 = 1 + 𝐶𝐷
2. k
3.
3. n
𝐶𝐵
𝐵𝐴
𝐶𝐷
𝐷𝐸
+ 𝐶𝐵 = 𝐶𝐷 + 𝐶𝐷
𝐶𝐵
𝐶𝐵+𝐵𝐴
𝐶𝐷+𝐷𝐸
= 𝐶𝐷
𝐶𝐵
4.
5. CA = CB + BA
CE = CD + DE
𝐶𝐴
𝐶𝐸
6. 𝐶𝐵 = 𝐶𝐷
4. m
7. ∠𝐶 ≅ ∠𝐶
8. ∆𝐶𝐵𝐷~∆𝐶𝐴𝐸
9. ∠𝐶𝐵𝐷 ≅ ∠𝐶𝐴𝐸
10. BD ║ AE
7. d
8. f
9. h
10. b
138.
139.
140.
141.
142.
143.
2. b
Reasons
1. c
5. l
6. i
50 feet
72 ft
90 ft
27.5 feet
40 ft
45 ft
Unit Review Answer Key
1.
2.
3.
4.
5.
6.
7.
8. c
9. a
10. a
11. d
12. x = 50 & z = 90
13. x = 18 & y = 22.5
14. 150 ft
c
b
c
b
b
d
c
Geometry: Triangles
~23~
NJCTL.org
15.
Statements
1. BD ║ AE
2. ∠𝐶 ≅ ∠𝐶
3. ∠𝐶𝐵𝐷 ≅ ∠𝐶𝐴𝐸
4. ∆𝐵𝐶𝐷~∆𝐴𝐶𝐸
Geometry: Triangles
Reasons
1. f
2. c
3. b
4. d
~24~
NJCTL.org