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Document 1805635
Chapter 3,
continued
b. Because the bars are parallel, the corresponding angles
between the bars and the foot are congruent. Because
the body and the foot are parallel, the bars act as
transversals, and so the alternate interior angles are
congruent. (See diagram.) This forces the foot to stay
parallel with the floor.
43. Ž 4>Ž 2 by the Alternate Interior Angles Theorem. Ž 2
> Ž 3 by the definition of angle bisector. Ž 5 > Ž 1 by
the Corresponding Angles Postulate. Ž 4 > Ž 5 is given,
so Ž 1 > Ž 2 > Ž 3 > Ž 4 > Ž 5. Because
mŽ 1 1 mŽ2 1 mŽ 3 5 1808, the measure of each angle
is 608. So, mŽ 1 5 608.
Mixed Review for TAKS
44. B;
Let * be the length and let w be the width of the original
rectangle.
40. a. Using the Alternate Interior Angles Theorem,
Pnew 5 2(2*) 1 2(2w)
5 2(2* 1 2w)
mŽ 2 5 mŽ 5 708. Ž 2 and Ž 3 are a linear pair,
so 708 1 mŽ3 5 1808, or mŽ 3 5 1108.
5 2(20)
5 40
b. Ž ABC is a straight angle because Ž 2 and Ž 3 are
supplementary, so the sum of the angle measures
is 1808.
c. If mŽ 1 is 608, Ž ABC will still be a straight angle
Copyright © by McDougal Littell, a division of Houghton Mifflin Company.
41.
42.
because Ž 2 and Ž 3 will still be supplementary. The
opening of the box will be more steep because the
measure of Ž 1 is smaller, so the slope of the line
becomes greater.
Statements
Reasons
1. n i p
1. Given
2. Ž1 > Ž3
2. Alternate Interior Angles
Theorem
3. mŽ 1 5 mŽ 3
3. Definition of congruent
angles
4. Ž 2 and Ž 3 form
a linear pair.
4. Definition of linear pair
5. mŽ 2 1 mŽ 3 5 1808
5. Linear Pair Postulate
6. mŽ 1 1 mŽ 2 5 1808
6. Substitution Property of
Equality
7.Ž 1 and Ž 2 are
supplementary.
7. Definition of
supplementary angles
The perimeter of the new rectangle is 40 feet.
45. F;
18x3y24
18
15
6x2z2
5y
6
5
}
5 }x3 2 1y24 2 1z2 5 }x2y25z2 5 }
5
22
15xyz
46. C;
The expression x 1 0.18x represents the total cost of a
meal including an 18% tip, where x is the cost of the food
in dollars.
Quiz 3.1–3.2 (p. 160)
Statements
Reasons
1. t >r, r i s
1. Given
2. Ž1 is a right angle.
2. Definition of perpendicular
lines
3. Ž1 > Ž 2
3. Corresponding Angles
Postulate
4. Ž 2 is a right angle.
4. Definition of congruent
angles
5. t > s
5. Definition of perpendicular
lines
1. Ž 2 and Ž 6 are corresponding angles.
2. Ž3 and Ž5 are consecutive interior angles.
3. Ž3 and Ž6 are alternate interior angles.
4. Ž2 and Ž7 are alternate exterior angles.
5. Using the Alternate Interior Angles Theorem:
2x8 5 1288
x 5 64
6. Using the Alternate Exterior Angles Theorem:
(2x 1 1)8 5 1518
2x8 5 1508
x 5 75
7. Using the Consecutive Interior Angles Theorem:
(7x 1 24)8 1 728 5 180
7x 5 84
x 5 12
Lesson 3.3
3.3 Guided Practice (pp. 161–164)
1. Yes. The measure of the angle corresponding to the
758 angle is 758 because it forms a linear pair with the
1058 angle. Then, corresponding angles are congruent
by defintion of congruent angles. So m i n by the
Corresponding Angles Converse.
2. Postulate 16 exchanges the hypothesis and conclusion
of Postulate 15, so Postulate 16 is the converse of
Postulate 15.
Geometry
Worked-Out Solution Key
59
Chapter 3,
continued
3. You can prove the lines are parallel using the Alternate
Exterior Angles Converse.
6. Using the Alternate Exterior Angles Converse:
(180 2 x)8 5 x8
4. You can prove the lines are parallel using the
180 5 2x
Corresponding Angles Converse.
5. Sample answer: You cannot prove the lines are parallel
because you do not know if Ž1 > Ž2, so you cannot use
the Alternate Interior Angles Converse.
90 5 x
The lines are parallel when x 5 90.
7. Using the Consecutive Interior Angles Converse:
2x8 1 x8 5 1808
6. Given: Ž1 > Ž8
3x 5 180
Prove: j i k
x 5 60
7. It is given that Ž4 > Ž5. By the Vertical Angles
Congruence Theorem, Ž1 > Ž4. Then by the Transitive
Property of Congruence, Ž1 > Ž5. So by the
Corresponding Angles Converse, g i h.
8. All of the steps are parallel. Since the bottom step is
parallel to the ground, the Transitive Property of Parallel
Lines applies and the top step is parallel to the ground.
3.3 Exercises (pp. 165–169)
Skill Practice
1.
t
The lines are parallel when x 5 60.
8. Using the Alternate Interior Angles Theorem:
(2x 1 20)8 5 3x8
20 5 x
The lines are parallel when x 5 20.
9. The student cannot conclude that lines a and b are
parallel because there is no indication that x equals y.
There is not enough information given in order to make
any conclusion.
10. Yes; Alternate Interior Angles Converse.
1 2
m
11. Yes; Alternate Exterior Angles Converse.
12. No, there is not enough information to prove m i n.
n
3 4
13. Yes; Corresponding Angles Converse.
14. No, there is not enough information to prove m i n.
2. Two lines cut by a transversal have congruent pairs
of alternate interior angles if and only if the lines
are parallel.
15. Yes; Alternate Exterior Angles Converse.
16. Answers will vary.
17. a. Using the Angle Addition Postulate,
mŽDCG 5 mŽDCE 1 mŽECG
5 388 1 778 5 1158.
Two lines cut by a transversal have congruent pairs
of alternate exterior angles if and only if the lines
are parallel.
Two lines cut by a transversal have supplementary pairs
of consecutive interior angles if and only if the lines
are parallel.
3. Using the Corresponding Angles Converse:
3x8 5 1208
Using the Linear Pair Postulate,
mŽCGH 1 1158 5 1808
mŽCGH 5 658.
b. ŽDCG and ŽCGH are consecutive interior angles
and they are supplementary.
c. @##$
DB i @##$
HF by the Consecutive Interior Angles Converse.
18. a.
x 5 40
l
m
The lines are parallel when x 5 40.
1
4. Using the Corresponding Angles Converse:
2
n
(2x 1 15)8 5 1358
2x 5 120
x 5 60
The lines are parallel when x 5 60.
5. Using the Consecutive Interior Angles Converse:
(3x 2 15)8 1 1508 5 1808
3x 5 45
x 5 15
The lines are parallel when x 5 15.
60
Geometry
Worked-Out Solution Key
b. Given: Ž1and Ž2 are supplementary.
Prove: m i n
19. Yes. You can prove a i b by using the Consecutive Interior
Angles Converse.
20. Yes. You can prove a i b by the Alternate Exterior Angles
Converse. Because the sum of 668 and 488 is 1148, the
alternate exterior angles are congruent.
21. There is not enough information to prove a i b.
Copyright © by McDougal Littell, a division of Houghton Mifflin Company.
Ž1 and Ž4, and Ž2 and Ž3 are Alternate Exterior
Angles.
Chapter 3,
continued
22. The angles shown as congruent do not show that
@##$
AD i @##$
BC. By the Alternate Interior Angles
AB i @##$
DC.
Converse, @##$
31.
23. D; There is not enough information given to make any of
the listed conclusions.
24. One angle measure must be given in order to find the
measure of every angle. Sample answer: Using the
Vertical Angles Congruence Theorem, the Linear Pair
Postulate, and the Corresponding Angles Postulate, the
other angle measures can be found.
25. Given: Ž1 and Ž7 are supplementary.
Statements
1. mŽ1 5 1158,
mŽ2 5 658
1. Given
2. 1158 1 658 5 1808
2. Addition
3. mŽ1 1 mŽ2 5 1808
3. Substitution
Property of Equality
4. Ž1 and Ž2 are
supplementary.
4. Definition of
supplementary angles
5. m i n
5. Consecutive Interior
Angles Converse
Prove: j i k
Show Ž1 congruent to Ž4 by the Vertical Angles
Congruence Theorem, and show Ž4 and Ž7 to be
supplementary by substitution. Then lines j and k are
parallel by the Consecutive Interior Angles Converse.
###$
26. EA i ###$
HC by the Corresponding Angles Converse because
ŽHEA > ŽGHC.
32. Because the alternate exterior angles are congruent, you
know that the bowling pins are set up in parallel lines by
the Alternate Exterior Angles Converse.
33. E. 20th Ave., E. 19th Ave., and E. 17th Ave. are all
parallel by the Corresponding Angles Converse.
E. 18th Ave. and E. 17th Ave. are parallel by the
Alternate Interior Angles Converse. All of the streets
are parallel to each other by the Transitive Property of
Parallel Lines.
###$
EB is not parallel to ###$
HD because ŽHEB is not congruent
to ŽGHD.
27. a. There is only one line through R perpendicular to
34.
plane ABC.
Reasons
b. There are infinitely many lines through R parallel to
plane ABC.
c. There is only one plane through R parallel to
Statements
1. Ž1 > Ž2
Ž3 > Ž4
1. Given
2. Ž2 > Ž3
2. Vertical Angles Congruence
Theorem
3. Ž1> Ž4
3. Transitive Property of Congruence
} }
4. AB i CD
4. Alternate Interior Angles Converse
plane ABC.
28. a. Using the Corresponding Angles Converse:
Reasons
Copyright © by McDougal Littell, a division of Houghton Mifflin Company.
(2x 1 2)8 5 (x 1 56)8
x 1 2 5 56
x 5 54
Lines p and q are parallel when x 5 54.
b. Using the Linear Pair Postulate and the Corresponding
35.
Statements
Reasons
1. a i b,
Ž2 > Ž3
1. Given
173 2 y 5 3y 2 17
2. Ž1 > Ž3
2. Alternate Interior Angles Theorem
173 5 4y 2 17
3. Ž1> Ž2
3. Transitive Property of Congruence
4. c i d
4. Corresponding Angles Converse
Angles Converse:
1808 2 (y 1 7)8 5 (3y 2 17)8
190 5 4y
47.5 5 y
Lines r and s are parallel when y 5 47.5.
c. Lines r and s cannot be parallel if lines p and q are
parallel. If lines p and q are parallel, x 5 54 and
y 5 63, but for lines r and s to be parallel, y must
equal 47.5.
Problem Solving
29. Because the alternate interior angles are congruent, you
know that the top of the picnic table is parallel to the
ground by the Alternate Interior Angles Converse.
30. Because the corresponding angles are congruent,
36. It is given that Ž1 > Ž8. Ž8 > Ž5 by the Vertical
Angles Congruence Theorem. Ž1 > Ž5 by the
Transitive Property of Congruence. So, m i n by the
Corresponding Angles Converse.
37. It is given that Ž 3 and Ž 5 are supplementary.
Ž 5 and Ž7 form a linear pair by the definition of a linear
pair. Žand Ž 7 are supplementary by the Linear Pair
Postulate. Ž 3 > Ž 7 by the Congruent Supplements
Theorem. So, m i n by the Corresponding Angles
Converse.
you know that line n is parallel to line m by the
Corresponding Angles Converse.
Geometry
Worked-Out Solution Key
61
38. a.
p
continued
q
1 3 5 7 9 11
2 4 6 8 10 12
r
Statements
t
b. Given: p i q and q i r
Prove: p i r
c.
Statements
Reasons
1. p i q, q i r
1. Given
2. Ž3 > Ž6
2. Alternate Interior Angles
Theorem
3. Ž6> Ž10
3. Corresponding Angles Postulate
5. Alternate Interior Angles
Converse
39. a. Because the corresponding angles formed by the blue
lines and the horizontal edge are congruent, you know
that the blue lines are parallel by the Corresponding
Angles Converse.
b. Slide the triangle along a fixed horizontal line using
the edge that forms a 908 angle to draw vertical
parallel lines.
40. Sample answer: Because the 1148 angle and the 668 angle
made by the transversal g are supplementary,
you can show that a i b by the Consecutive Interior
Angles Converse.
41. Sample answer: Because the two corresponding 668
angles made by the transversal g are congruent, you can
show that b i c by the Corresponding Angles Converse.
42. Sample answer: Because the two corresponding 1378
angles (718 1 668 5 1378) made by the transversal b are
congruent, you can show that d i f by the Corresponding
Angles Converse.
43. Sample answer: Because the two corresponding 668
angles (1808 2 1148 5 668) made by the transversal b are
congruent, you can show that e i g by the Corresponding
Angles Converse.
44. Sample answer: Because a i b and b i c, you can show
that a i c by the Transitive Property of Parallel Lines.
45. a. Sample answer:
T
P
n
S
PR bisects ŽQPT,
1. * i n, ###$
and ###$
QS bisects ŽPQU
1. Given
2. ŽQPT > ŽPQU
2. Alternate Interior
Angles Theorem
3. ŽQPR > ŽRPT and
ŽPQS > ŽSQU
3. Definition of angle
bisector
4. Definition of
4. m ŽQPT 5 mŽPQU,
congruent angles
mŽQPR 5 mŽRPT, and
mŽPQS 5 mŽSQU
4. Ž 3 > Ž 10 4. Substitution Property of
Congruence
5. p i r
Reasons
5. mŽQPT 5 mŽQPR
1 mŽRPT; mŽPQU 5
mŽPQS 1 mŽSQU
5. Angle Addition
Postulate
6. mŽQPR 1 mŽRPT
5 mŽPQS 1 mŽSQU
6. Substitution Property
of Equality
7. mŽQPR 1 mŽQPR
5 mŽPQS 1 mŽPQS
7. Substitution Property
of Equality
8. 2 + mŽQPR 5
2 + mŽPQS
8. Distributive Property
9. mŽQPR 5 mŽPQS
9. Division Property
of Equality
10. ŽQPR > ŽPQS
10. Definition of
congruent angles
11. ###$
PR i ###$
QS
11. Alternate Interior
Angles Converse
Mixed Review for TAKS
46. C;
Number
Material
Selling
Number
Total
of frames 2 cost per + of frames
price
per
+
5
earnings
sold
frame
frame
decorated
t
5
5
+
y
2
2.75 +
x
47. G;
a2 1 b2 5 c2
132 1 362 5 c2
1465 5 c 2
38.3 ø c
}
The length of BD is about 38.3 feet.
Mixed Review for TEKS (p. 170)
1. B;
Lines m and q are skew.
R
U
b. Conjecture: The angle bisectors of a pair of alternate
interior angles are parallel.
PR bisects ŽQPT, and ###$
QS
Given: * i n, ###$
bisects ŽPQU.
PR i ###$
QS
Prove: ###$
62
Geometry
Worked-Out Solution Key
2. H;
Ž4 > Ž1 by the Alternate Exterior Angles Theorem.
3. B;
Ž1 > Ž2 by the Alternate Exterior Angles Theorem.
So, mŽ2 5 mŽ1 5 538.
Copyright © by McDougal Littell, a division of Houghton Mifflin Company.
Chapter 3,
Chapter 3,
continued
3.4 Exercises (pp. 175–178)
4. H;
Because Ž1 and Ž2 are congruent alternate interior
angles, you know that p i q by the Alternate Interior
Angles Converse.
5. A;
Using the Alternate Interior Angles Converse:
(6x 1 5)8 5 238
6x 5 18
x53
Lines * and m are parallel when x 5 3.
6. Using the Linear Pair Postulate, mŽ2 5 1808 2 838 5
978. Using the Corresponding Angles Postulate,
mŽ1 5 mŽ2 5 978.
Lesson 3.4
change to horizontal change between any two points on
the line.
2. When you apply the slope formula to a horizontal line,
the numerator of the resulting fraction is zero, so the
slope is zero. When you apply the slope formula to a
vertical line, the denominator of the resulting fraction is
zero, so the slope is undefined.
3. D; m is positive.
4. A; m is negative.
5. B; m is zero.
y2 2 y1
625
1
7. m 5 } 5 } 5 }
x2 2 x1
523
2
6. C; m is undefined.
1
1. Slope of line b:
y2 2 y1
420
m5}
5}
52
x2 2 x1
624
2. Slope of line c:
y2 2 y1
424
m5}
5}
50
x2 2 x1
620
y2 2 y1
123
2
3. Slope of line m: m1 5 } 5 } 5 2}
5
x2 2 x1
4 2 (21)
y2 2 y1
23 2 (21)
2
Slope of line t: m2 5 }
5}
5 2}5
x2 2 x1
3 2 (22)
Because m and t have the same slope, they are parallel.
Copyright © by McDougal Littell, a division of Houghton Mifflin Company.
1. The slope of a non-vertical line is the ratio of vertical
The slope is }2.
3.4 Guided Practice (pp. 171–174)
y2 2 y1
522
3
1
4. Slope of line n: m1 5 } 5 } 5 } 5 }
x2 2 x1
620
6
2
y2 2 y1
024
24
Slope of line m: m2 5 }
5}
5}
5 22
x2 2 x1
422
2
Because the product of m1 and m2 is 21, n > m.
5. The parachute in jump c was in the air approximately
1.25 seconds longer than the parachutes in jumps a and
b. So, the parachute in jump c was in the air for the
longest time.
6. The x-intercepts represent the time (in minutes) that
it takes each parachute to reach the ground. You can
eliminate choice B, because jumps b and c do not have
the same x-intercept, so the parachutes were not open for
the same amount of time.
y2 2 y1
520
5
7. Slope of line q: m1 5 } 5 } 5 2}
x2 2 x1
24 2 0
4
y2 2 y1
720
7
Slope of line t: m2 5 }
5}
5 2}
x2 2 x1
210 2 0
10
Line q is steeper because the absolute value of the slope
of its line is greater.
rise
Skill Practice
300
350
8. Slope 5 }
run 5 } 5 0.857
The roller coaster is more steep than the Magnum
because the slope of its line is greater (0.875 > 0.5125).
The roller coaster is less steep than the Millenium Force
because the slope of its line is less (0.875 < 1).
y2 2 y1
26 2 2
28
8. m 5 } 5 } 5 } 5 22
x2 2 x1
4
2 2 (22)
The slope is 22.
y2 2 y1
21 2 (21)
0
9. m 5 } 5 } 5 } 5 0
x2 2 x1
8
3 2 (25)
The slope is 0.
y2 2 y1
621
5
5
10. m 5 } 5 } 5 } 5 2}
x2 2 x1
022
22
2
5
The slope is 2}2.
run
11. The slope of the line was computed using } instead
rise
rise
3
.
of }
run . The rise is 3 and the run is 4, so the slope is }
4
12. The values of x2 and x1 were interchanged when
computing the slope.
y2 2 y1
725
2
m5}
5}
5}
5 21
x 2x
224
22
2
1
y2 2 y1
420
2
13. Slope of line 1: m1 5 } 5 } 5 }
x2 2 x1
721
3
y2 2 y1
620
6
3
Slope of line 2: m2 5 }
5}
5}
5 2}2
x2 2 x1
327
24
2
3
Because m1m2 5 }3 + 2}2 5 21, the lines
are perpendicular.
y2 2 y1
3
22 2 1
14. Slope of line 1: m1 5 } 5 } 5 }
x2 2 x1
4
27 2 (23)
y2 2 y1
4 2 (21)
5
Slope of line 2: m2 5 }
5}
5 }6
x2 2 x1
822
Because m1 Þ m2 and m1m2 Þ 21, the lines are neither
parallel nor perpendicular.
y2 2 y1
723
4
15. Slope of line 1: m1 5 } 5 } 5 } 5 1
x2 2 x1
4
25 2 (29)
y2 2 y1
226
24
5}
5}
5 21
Slope of line 2: m2 5 }
x2 2 x1
4
27 2 (211)
Because m1m2 5 1 + (21) 5 21, the lines
are perpendicular.
Geometry
Worked-Out Solution Key
63
Fly UP