Answers
8.
9.
8.
15°
15°
120°
75°
75°
120°
9.
150°
150°
10. a.
10. Sample answer:
1
3
4
2
5
11. 75°
b.
7.1 Enrichment and Extension
1. Angle A is an acute angle.
2 – 5.
B
c.
G
A
C
6. Angle BAC measures 60°. Each angle formed from
the bisection measures 30°.
11. ∠1 = 48°,
∠ 2 = 132°,
7.1 Puzzle Time
∠3 = 48°
A SNEAKER
7.1 Practice B
7.2 Start Thinking!
1. Sample answer: adjacent: ∠ IED and ∠ DEF ;
∠ FEG and ∠GEH ; vertical: ∠ DEF and ∠GEH ;
∠ FEG and ∠ DEH
2. Sample answer: adjacent: ∠ SUT and ∠ SUZ ;
∠ XUY and ∠WUX ; vertical: ∠ SUZ and ∠WUX ;
∠YUZ and ∠VUW
3. adjacent; 123
4. adjacent; 10
5. adjacent; 45
6. vertical; 30
For use before Activity 7.2
Sample answer: Two angles are adjacent angles when
they share common sides and have the same vertex.
Two angles are vertical angles when they are opposite
angles formed by the intersection of two lines. Vertical
angles are congruent angles, meaning they have the
same measure.
7.2 Warm Up
For use before Activity 7.2
1.
2.
120°
7.
45°
45°
120°
100°
100°
3.
160°
4.
30°
30°
160°
A36 Big Ideas Math Red
Answers
Copyright © Big Ideas Learning, LLC
All rights reserved.
Answers
7.2 Start Thinking!
7.2 Practice B
For use before Lesson 7.2
complementary; supplementary; Answers will vary.
Sample answers: A letter S is like two Cs put together,
so the sum of supplementary angles is twice as much as
complementary angles. “It’s right to give a compliment.”
C comes before S in the alphabet and 90 comes before
180 on a number line.
1. neither
2. complementary
3. supplementary
4. supplementary
5. supplementary; x = 11 6. complementary; x = 6
7. 60°
8. x = 5; y = 5
9. a. x + c = 90
7.2 Warm Up
For use before Lesson 7.2
b. x + s = 180
7.2 Enrichment and Extension
1. sometimes; x may be acute or obtuse.
1. 130°
2. 50°
3. 50°
4. 30°
2. always; y must be between 0° and 90°.
5. 70°
6. 50°
7. 60°
8. 40°
3. never; If x = 90° and y < 90°, then
9. 40°
10. 50°
11. 50°
12. 130°
x + y < 180°.
13. 140°
4. sometimes; The sum x + y could be any value
between 90° and 270°.
14. 40°
15. 140°
7.2 Puzzle Time
LEAP YEAR
7.2 Practice A
1. sometimes; y could be right, acute, or obtuse.
7.3 Start Thinking!
For use before Activity 7.3
2. never; x must be between 0° and 90°.
Sample answer: A yield sign is an equilateral triangle.
3. complementary
4. neither
7.3 Warm Up
5. neither
6. supplementary
7. angle x: 52°; angle y: 38°
8. complementary; x = 5
9. supplementary; x = 20
10.
For use before Activity 7.3
1–6. Check students’ work.
7.3 Start Thinking!
For use before Lesson 7.3
90°; Sample answer: Begin by drawing the angle with
measure 30°. Then draw the second angle of 60° off
one of the rays. Measure the third angle. The third angle
measure is 90°.
7.3 Warm Up
130°
50°
For use before Lesson 7.3
1– 4. Check students’ work.
11.
7.3 Practice A
1. equiangular, equilateral, acute
2. obtuse, scalene
110° 70°
3. right, scalene
4. isosceles, acute
12.
135°
45°
13. complementary: 45°; supplementary: 90°
Copyright © Big Ideas Learning, LLC
All rights reserved.
Big Ideas Math Red
Answers
A37