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Geo_Book_Answers

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22. The platform stays parallel to the floor<br />

because opposite sides of a rectangle are parallel<br />

(a rectangle is a parallelogram).<br />

23. The crosswalks form a parallelogram: The<br />

streets are of different widths, so the crosswalks are<br />

of different lengths. The streets would have to meet<br />

at right angles for the crosswalks to form a rectangle.<br />

The corners would have to be right angles and the<br />

streets would also have to be of the same width for<br />

the crosswalk to form a square.<br />

24. Place one side of the ruler along one side of<br />

the angle. Draw a line with the other side of the<br />

ruler. Repeat with the other side of the angle. Draw<br />

a line from the vertex of the angle to the point<br />

where the two lines meet.<br />

25. Rotate your ruler so that each endpoint of the<br />

segment barely shows on each side of the ruler.<br />

Draw the parallel lines on each side of your ruler.<br />

Now rotate your ruler the other way and repeat the<br />

process to get a rhombus. The original segment is<br />

one diagonal of the rhombus. The other diagonal<br />

will be the perpendicular bisector of the original<br />

segment.<br />

26. See flowchart below.<br />

27. Yes, it is true for rectangles.<br />

Given: 1 2 3 4<br />

Show: ABCD is a rectangle<br />

By the Quadrilateral Sum Conjecture, m1 <br />

m2 m3 m4 360°. It is given that all<br />

four angles are congruent, so each angle measures<br />

26. (Lesson 5.6)<br />

1<br />

2<br />

3<br />

QU AD<br />

Given<br />

QD AU<br />

?<br />

?<br />

Given SSS<br />

DU DU<br />

Same segment<br />

4<br />

QUD ADU<br />

8<br />

Given<br />

5<br />

1 2<br />

3 4<br />

? CPCTC<br />

QU UA AD DQ<br />

90°. Because 4 and 5 form a linear pair,<br />

m4 m5 180°. Substitute 90° for m4 and<br />

solve to get m5 90°. By definition of congruent<br />

angles, 5 3, and 5 and 3 are alternate<br />

interior angles, so AD BC by the Converse of the<br />

Parallel Lines Conjecture. Similarly, 1 and 5 are<br />

congruent corresponding angles, so AB CD by the<br />

Converse of the Parallel Lines Conjecture. Thus,<br />

ABCD is a parallelogram by the definition of<br />

parallelogram. Because it is an equiangular<br />

parallelogram, ABCD is a rectangle.<br />

28. a 54°, b 36°, c 72°, d 108°, e 36°,<br />

f 144°, g 18°, h 48°, j 48°, k 84°<br />

29. possible answers: (1, 0); (0, 1); (1, 2); (2, 3)<br />

30. y 8 6<br />

x<br />

9<br />

8 <br />

9<br />

or 8x 9y 86<br />

7<br />

31. y x 10<br />

12<br />

<br />

5<br />

or 7x 10y 24<br />

32. velocity 1.8 mi/h; angle of path 106.1°<br />

clockwise from the north<br />

60<br />

1.5 mi/h<br />

2 mi/h<br />

6<br />

QU AD<br />

7 QUAD is a<br />

QD AU<br />

parallelogram<br />

Converse of the<br />

Parallel Lines<br />

Conjecture<br />

9<br />

Definition of<br />

rhombus<br />

Definition of<br />

parallelogram<br />

QUAD is a<br />

rhombus<br />

?<br />

ANSWERS TO EXERCISES 69<br />

<strong>Answers</strong> to Exercises

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