NAME ______________________________________________ DATE
3-1
____________ PERIOD _____
Study Guide and Intervention Parallel Lines and Transversals
Relationships Between Lines and Planes
n P
Q
m
S
R
Example
B
a. Name all planes that are parallel to plane ABD. plane EFH b. Name all segments that are parallel to C G . F B , D H , and A E
C
F
G
A
D
E
H
c. Name all segments that are skew to E H . F B , C G , B D , CD , and A B
Exercises For Exercises 1–3, refer to the figure at the right.
N
1. Name all planes that intersect plane OPT.
O
U M
2. Name all segments that are parallel to N U .
T P
R
S
3. Name all segments that intersect M P .
For Exercises 4–7, refer to the figure at the right.
N M
4. Name all segments parallel to Q X .
E
H Q
T
5. Name all planes that intersect plane MHE.
O
X R A
S G
6. Name all segments parallel to Q R .
7. Name all segments skew to A G .
©
Glencoe/McGraw-Hill
125
Glencoe Geometry
Lesson 3-1
When two lines lie in the same plane and do not intersect, they are parallel. Lines that do not intersect and are not coplanar are skew lines. In the figure, is parallel to m, or || m. You can also write || RS . Similarly, if two planes do not intersect, they are PQ parallel planes.
NAME ______________________________________________ DATE
3-2
____________ PERIOD _____
Practice Angles and Parallel Lines
In the figure, m2 92 and m12 74. Find the measure of each angle. 1. 10
4 3 5 6
2. 8
3. 9
4. 5
5. 11
6. 13
1
m
2 8
7
n
12 11 13 14 10 15 9 16 r
s
Find x and y in each figure. 7.
(9x 12)
8. (5y 4)
3x (4y 10)
3y
(2x 13)
Find m1 in each figure. 9.
10. 50 62 1
1
144
100
11. PROOF Write a paragraph proof of Theorem 3.3. Given: || m , m || n Prove: 1 12
k 1 2 3 4
5 6 7 8
m
9 10 11 12
n
12. FENCING A diagonal brace strengthens the wire fence and prevents it from sagging. The brace makes a 50° angle with the wire as shown. Find y.
50
y
©
Glencoe/McGraw-Hill
134
Glencoe Geometry
NAME ______________________________________________ DATE
3-2
____________ PERIOD _____
Study Guide and Intervention
(continued)
Angles and Parallel Lines Algebra and Angle Measures
Algebra can be used to find unknown values in angles formed by a transversal and parallel lines.
Example
If m1 3x 15, m2 4x 5, m3 5y, and m4 6z 3, find x and y. p || q, so m1 m2 because they are corresponding angles.
r || s, so m2 m3 because they are corresponding angles.
3x 15 3x 15 3x 15 15 5 20
m2 m3 75 5y
4x 5 4x 5 3x x5 x55 x
p
q 1
2 4
r 3
s
75 5y 5 5
15 y
Exercises Find x and y in each figure. 1.
2. (5x 5) (6y 4)
(15x 30)
90
(3y 18)
10x
(4x 10)
3.
(11x 4)
(5y 5)
4. 2y
(13y 5)
5x
3x
4y
(5x 20)
Find x, y, and z in each figure. 5.
6. 2y
(4z 6)
z
2x 90 x
x 106 2y
©
Glencoe/McGraw-Hill
132
Glencoe Geometry
NAME ______________________________________________ DATE
3-3
____________ PERIOD _____
Practice Slopes of Lines
Determine the slope of the line that contains the given points. 2. I(2, 9), P(2, 4)
1. B(4, 4), R(0, 2) Find the slope of each line. 3. LM
y
M
4. GR L
S
5. a line parallel to GR
O
6. a line perpendicular to PS
P
x
G R
and ST are parallel, perpendicular, or neither. Determine whether KM 7. K(1, 8), M(1, 6), S(2, 6), T(2, 10) 9. K(4, 10), M(2, 8), S(1, 2), T(4, 7)
8. K(5, 2), M(5, 4), S(3, 6), T(3, 4) 10. K(3, 7), M(3, 3), S(0, 4), T(6, 5)
Graph the line that satisfies each condition. 1 2
11. slope , contains U(2, 2)
4 3
12. slope , contains P(3, 3)
y
y
O
O
x
x
U (2, –2) P(–3, –3)
13. contains B(4, 2), parallel to FG with F(0, 3) and G(4, 2)
14. contains Z(3, 0), perpendicular to EK with E(2, 4) and K(2, 2) y
y
E(–2, 4) B (–4, 2)
Z (–3, 0) O
O
x
x
K(2, –2)
G(4, –2) F(0, –3)
15. PROFITS After Take Two began renting DVDs at their video store, business soared. Between 2000 and 2003, profits increased at an average rate of $12,000 per year. Total profits in 2003 were $46,000. If profits continue to increase at the same rate, what will the total profit be in 2009? ©
Glencoe/McGraw-Hill
140
Glencoe Geometry
NAME ______________________________________________ DATE
3-4
____________ PERIOD _____
Study Guide and Intervention Equations of Lines
Write Equations of Lines You can write an equation of a line if you are given any of the following: • the slope and the y-intercept, • the slope and the coordinates of a point on the line, or • the coordinates of two points on the line. If m is the slope of a line, b is its y-intercept, and (x1, y1) is a point on the line, then: • the slope-intercept form of the equation is y mx b, • the point-slope form of the equation is y y1 m(x x1).
Example 1
Write an equation in slope-intercept form of the line with slope 2 and y-intercept 4. y mx b Slope-intercept form y 2x 4 m 2, b 4 The slope-intercept form of the equation of the line is y 2x 4.
Example 2
Write an equation in point-slope form of the line with slope 3 that contains (8, 1). 4
y y1 m(x x1) 3 4
y 1 (x 8)
Point-slope form 3 4
m , (x1, y1) (8, 1)
The point-slope form of the equation of the 3 line is y 1 (x 8). 4
Exercises Write an equation in slope-intercept form of the line having the given slope and y-intercept. 1. m: 2, y-intercept: 3
1 4
4. m: 0, y-intercept: 2
1 3
5. m: , y-intercept:
6. m: 3, y-intercept: 8
Write an equation in point-slope form of the line having the given slope that contains the given point. 1 2
7. m , (3, 1)
9. m 1, (1, 3)
5 2
11. m , (0, 3)
©
Glencoe/McGraw-Hill
8. m 2, (4, 2)
1 4
10. m , (3, 2)
12. m 0, (2, 5)
143
Glencoe Geometry
Lesson 3-4
3. m: , y-intercept: 5
5 3
1 2
2. m: , y-intercept: 4
NAME ______________________________________________ DATE
3-4
____________ PERIOD _____
Study Guide and Intervention
(continued)
Equations of Lines Write Equations to Solve Problems
Many real-world situations can be modeled
using linear equations.
Example
Donna offers computer services to small companies in her city. She charges $55 per month for maintaining a web site and $45 per hour for each service call. a. Write an equation to represent the total monthly cost C for maintaining a web site and for h hours of service calls. For each hour, the cost increases $45. So the rate of change, or slope, is 45. The y-intercept is located where there are 0 hours, or $55. C mh b 45h 55
b. Donna may change her costs to represent them by the equation C 25h 125, where $125 is the fixed monthly fee for a web site and the cost per hour is $25. Compare her new plan to the old one 1 2
if a company has 5 hours of service calls. Under which plan would Donna earn more? First plan 1 2
For 5 hours of service Donna would earn
12
C 45h 55 45 5 55 247.5 55 or $302.50 Second Plan 1 2
For 5 hours of service Donna would earn C 25h 125 25(5.5) 125 137.5 125 or $262.50 Donna would earn more with the first plan.
Exercises For Exercises 1–4, use the following information. Jerri’s current satellite television service charges a flat rate of $34.95 per month for the basic channels and an additional $10 per month for each premium channel. A competing satellite television service charges a flat rate of $39.99 per month for the basic channels and an additional $8 per month for each premium channel.
©
1. Write an equation in slope-intercept form that models the total monthly cost for each satellite service, where p is the number of premium channels.
2. If Jerri wants to include three premium channels in her package, which service would be less, her current service or the competing service?
3. A third satellite company charges a flat rate of $69 for all channels, including the premium channels. If Jerri wants to add a fourth premium channel, which service would be least expensive?
4. Write a description of how the fee for the number of premium channels is reflected in the equation.
Glencoe/McGraw-Hill
144
Glencoe Geometry
NAME ______________________________________________ DATE
3-5
____________ PERIOD _____
Practice Proving Lines Parallel
Given the following information, determine which lines, if any, are parallel. State the postulate or theorem that justifies your answer. 1. mBCG mFGC 180
2. CBF GFH
3. EFB FBC
4. ACD KBF
Find x so that || 5. (3x 6)
B E
F H
D
C G J
m. t m
(4x 6)
A
K
6.
7.
t
(2x 12) (5x 15)
(5x 18) (7x 24)
m
t
m
8. PROOF Write a two-column proof. Given:2 and 3 are supplementary. Prove: A B || C D D 1 2
B
3
4 C 5 6
A
9. LANDSCAPING The head gardener at a botanical garden wants to plant rosebushes in parallel rows on either side of an existing footpath. How can the gardener ensure that the rows are parallel?
©
Glencoe/McGraw-Hill
152
Glencoe Geometry
NAME ______________________________________________ DATE
3-5
____________ PERIOD _____
Study Guide and Intervention Proving Lines Parallel
Identify Parallel Lines If two lines in a plane are cut by a transversal and certain conditions are met, then the lines must be parallel. If • • • • •
then corresponding angles are congruent, alternate exterior angles are congruent, consecutive interior angles are supplementary, alternate interior angles are congruent, or two lines are perpendicular to the same line,
the lines are parallel.
Example 1
Example 2 so that m || n .
If m1 m2, determine which lines, if any, are parallel. s r 2
1
m
m
D (3x 10)
n B
n
Find x and mABC
A
(6x 20)
C
We can conclude that m || n if alternate interior angles are congruent.
Since m1 m2, then 1 2. 1 and 2 are congruent corresponding angles, so r || s.
mDAB 3x 10 10 30 10
mCDA 6x 20 3x 20 3x x
mABC 6x 20 6(10) 20 or 40
Exercises 1.
m.
(8x 8) (9x 1)
m
3.
(4x 20)
(6x 20)
4.
m
2.
(5x 5)
m
(3x 15)
6x
5.
2x
m
6. m
(5x 20)
(3x 20)
m n
70
©
Glencoe/McGraw-Hill
149
Glencoe Geometry
Lesson 3-5
Find x so that ||
NAME ______________________________________________ DATE
3-5
____________ PERIOD _____
Study Guide and Intervention
(continued)
Proving Lines Parallel Prove Lines Parallel You can prove that lines are parallel by using postulates and theorems about pairs of angles. You also can use slopes of lines to prove that two lines are parallel or perpendicular. Example a Given: 1 2, 1 3
A
B 3
Prove: A B || D C 1
8
2
D
Statements 1. 1 2 1 3 2. 2 3 3. A B || D C
b. Which lines are parallel? Which lines are perpendicular?
C
y
P (–2, 4) 4
Reasons 1. Given
–8
–4
S (–8, –4)
2. Transitive Property of 3. If alt. int. angles are , then the lines are ||.
Q (8, 4)
O
4
–4
8
x
R(2, –4)
–8
slope of P Q 0
slope of S R 0
4 S slope of P 3
slope of Q R
slope of P R 2
4 3 1 slope of S Q 2
So P Q || S R , P S || Q R , and P R ⊥S Q .
Exercises For Exercises 1–6, fill in the blanks. Given: 1 5, 15 5 Prove: || m , r || s Statements
r
s 1 2 4 3
9 10 12 11
5 6 8 7
Reasons
1. 15 5
1.
2. 13 15
2.
3. 5 13
3.
4. r || s
4.
5.
5. Given
6.
6. If corr are , then lines ||.
⊥ TQ . Explain why or why not. 7. Determine whether PQ
13 14 16 15
m
y
P
Q
T O
©
Glencoe/McGraw-Hill
150
x
Glencoe Geometry
NAME ______________________________________________ DATE
3-6
____________ PERIOD _____
Skills Practice
Draw the segment that represents the distance indicated. 1. B to AC
2. G to EF
B
3. Q to SR
E
A
F
D
C
P
S
G
Q
R
Construct a line perpendicular to through K. Then find the distance from K to . 4.
5.
y
y
K K O
x
x
O
Find the distance between each pair of parallel lines. 6. y 7 y 1
9. y 5x y 5x 26
©
Glencoe/McGraw-Hill
7. x 6 x5
8. y 3x y 3x 10
10. y x 9 yx3
11. y 2x 5 y 2x 5
157
Glencoe Geometry
Lesson 3-6
Perpendiculars and Distance
