1. Segments, Rays, Parallel Lines and Planes
GEOMETRY LESSON 1-3
Pages Exercises 1. 2. 3. 4.
5. RS, RT, RW, ST, SW, TW
6. RS, ST, TW, WT, TS, SR
7. a. TS or TR, TW
b. SR, ST
8. 4; RY, SY, TY, WY
9. Answers may vary.
Sample: 2; YS or YR, YT or YW
10. Answers may vary.
Check students’ work.
11. DF
12. BC
13. BE, CF
14. DE, EF, BE
15. AD, AB, AC
16. BC, EF
17. ABC || DEF
1-3

2. Segments, Rays, Parallel Lines and Planes
GEOMETRY LESSON 1-3
18-20 Answers may vary. Samples are given
25. true
26. False; they are skew.
27. true
28. False; they intersect above CG.
29. true
30. False; they intersect above pt. A.
18. BE || AD
19. CF, DE
20. DEF, BC
21. FG
22. Answers may vary. Sample: CD, AB
23. BG, DH, CL
24. AF
31. False; they are ||.
32. False; they are ||.
33. Yes; both name the segment with endpoints X and Y.
34. No; the two rays have different endpoints.
35. Yes; both are the line through pts. X and Y.
1-3

3. Segments, Rays, Parallel Lines and Planes
GEOMETRY LESSON 1-3
36.
37. always
38. never
39. always
40. always
41. never
42. sometimes
43. always
44. sometimes
45. always
46. sometimes
47. sometimes
48. Answers may vary. Sample: (0, 0); check students’ graphs.
49. a. Answers may vary. Sample: northeast and southwest
b. Answers may vary. Sample: northwest and southeast, east and west
50. Two lines can be parallel, skew, or intersecting in one point. Sample: train tracks–parallel; vapor trail of a northbound jet and an eastbound jet at different altitudes– skew; streets that cross–intersecting
1-3

4. Segments, Rays, Parallel Lines and Planes
GEOMETRY LESSON 1-3
55. a. The lines of intersection are parallel.
b. Examples may vary. Sample: The floor and ceiling are parallel. A wall intersects both. The lines of intersection are parallel.
56. Answers may vary. Sample: The diamond structure makes it tough, strong, hard, and durable. The graphite structure makes it soft and slippery.
57. a.
one segment; EF b.
3 segments; EF, EG, FG
51. Answers may vary. Sample: Skew lines cannot be contained in one plane. Therefore, they have “escaped” a plane.
52. ST || UV
53. Answers may vary.
Sample: XY and ZW
intersect at R.
54. Planes ABC and DCBF
intersect in BC.
1-3

5. Segments, Rays, Parallel Lines and Planes
GEOMETRY LESSON 1-3
58. No; two different planes cannot intersect in more than one line.
59. yes; plane P, for example
60. Answers may vary.
Sample: VR, QR, SR
61. QR
62. Yes; no; yes; explanations may vary.
63. D
64. H
65. B
66. F
67. B
68. C
69. D
57. c.
Answers may vary. Sample: For each “new” point, the number of new segments equals the number of “old” points.
d. 45 segments e.
n(n – 1) 2
1-3

6. Segments, Rays, Parallel Lines and Planes
GEOMETRY LESSON 1-3
70. [2] a. Alike: They do not intersect.
Different: Parallel lines are coplanar and skew lines lie in different planes.
b. No; of the 8 other lines shown, 4 intersect
JM and 4 are skew to JM.
[1] one likeness, one difference
71–78. Answers may vary. Samples are given.
71. EF
72. A
73. C
74. AEF and HEF
75. ABH
76. EHG
77. FG
78. B
79.
80.
81.
, 1.48
83. –22, –29
84. FG, GH
85. P, S
86. No; whenever you subtract a negative number, the answer is greater than the given number. Also, if you subtract 0, the answer stays the same.
1-3