Segments, Rays, Parallel Lines and Planes GEOMETRY LESSON 1-3 Pages 19-23 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

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

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

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

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

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. 82. 1.4, 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