1. Parallel and Perpendicular Lines
ALGEBRA 1 LESSON 6-5
pages 314–317  Exercises 1.
2. –
3. 1
4. 0
5. –
6. 7
7. no, different slopes
8. yes, same slopes and
different y-intercepts
9. yes, same slopes and
10. no, different slopes
11. yes, same slopes and
12. yes, same slopes and
13. y = 6x
14. y = –3x + 9
15. y = –2x – 1
16. y = – x – 20
17. y = 0.5x – 9
18. y = – x +
19. –
20.
21. –
22. 5 1 2 3 4
23.
24. undefined
25. y = – x
26. y = –x + 10
27. y = 3x – 10
28. y = x +
29. y = – x + 24
30. y = – x + 2
31. y = x + 1
32. perpendicular
33. parallel
34. perpendicular 7 5 11
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2. Parallel and Perpendicular Lines
ALGEBRA 1 LESSON 6-5
35. neither
36. parallel
37. perpendicular
38. parallel
39. neither
40. perpendicular
41. neither
42. Answers may vary.
Sample: same x
and y coefficients
43. y = – x – ;
y = – x +
44. y = x +
y = –3x + 7
45. y = – x
y = 2x
46. y = x + ;
y = x –
47. y = 4; y = 2
48. y = x; y = –x + 1
49. about
50. Answers may vary.
Sample: same slope
of –
51. Answers may vary.
Sample: • – = –1 4 5 19 3 1
52. a. The screen is not
square.
b. The lines appear
perpendicular.
53. Answers may vary.
Sample: y = 4x + 1
54. No; the slopes are not equal.
55. No; the slopes are not
neg. reciprocals.
56. yes; same slopes and
different y-intercepts
57. False; the product of two
positive numbers can’t
be –1.
58. True; y = x + 2 and
y = x + 3 are parallel. 2 21 /
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3. Parallel and Perpendicular Lines
ALGEBRA 1 LESSON 6-5
59. False; all direct variations
go through the point (0, 0).
If they have the same slope,
they are the same line,
not parallel lines.
60. The slopes of AD and BC
are both undefined, so
they are parallel. The
slopes of AB and CD are
both so they are
parallel. The quadrilateral
is a parallelogram. 2 5
61. The slope of JK is .
The slope of KL is –2.
The slope of LM is .
The slope of JM is –4.
The quadrilateral is not
a parallelogram.
62. The slopes of PQ and
RS are both – .The
slopes of QR and SP
are both – .The
quadrilateral is 1 6 3
63. The slopes of AB and
CD are both .The
slopes of BC and AD
are both – . The
product is –1, so
the quadrilateral is a
rectangle.
64. The slopes of KL and
MN are both – .The
slopes of LM and KN
are both 5. The
product is not –1, so
the quadrilateral is not
a rectangle.
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4. Parallel and Perpendicular Lines
ALGEBRA 1 LESSON 6-5
The diagonal AC has
a slope of . The
diagonals are
perpendicular.
ABCD is a rhombus.
67. RP has a slope of .
RQ has a slope
of – . RP is the neg.
reciprocal of RQ, so
PQR is a right
triangle.
68. parallel
69. perpendicular
65. The slopes of PQ and RS
are both . The slopes
of PS and QR are both –2.
The product is –1, so
the quadrilateral is a
rectangle.
66. BC and AD both have
a slope of zero. BC and
AD are parallel. AB and
CD both have a slope
of . AB and CD are
parallel. The diagonal BD
has a slope of –2. 1 2 4 3
70. y = – x – ;
y = x + 7
71. y = x – 3;
y = –2x + 7
72. –1.5; 24
73. D
74. F
75. C 8 17
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5. Parallel and Perpendicular Lines
ALGEBRA 1 LESSON 6-5
76. [2] Find slope of
2x + y = 3:
y = –2x + 3, therefore
slope is –2.
Find x: = –2,
= –2,
–4 = –2 + 2x,
x = –1 (OR equivalent
explanation)
[1] correct value of x but
no work OR minor
computation error in work
77. C
78. A
79. B
80. y = 3x + 4
81. y = –4x – 8
82. y + 3 = (x – 5)
83. y + 9 = – (x + 1)
84. y – 4 = – (x + 6)
85. y – 11 = (x – 7)
86. 7; 11; 15
87. –9; –17; –25
88. yes
2 – 6
1 – x
– 4
89. yes
90. no
91. yes 3 4 2 5 1
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