Download 8-5 practice b triangles

MSM07G6_RESBK_Ch08_037-045.pe
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Name
LESSON
Date
Class
Practice B
8-5 Triangles
Use the diagram to find the measure of each indicated angle.
1. !CBD
90°
2. !DAC
45°
3. !ABC
90°
4. !EBA
90°
5. !ACB
45°
D
E
B
45°
45°
C
A
Classify each triangle using the given information.
6. The perimeter of the
triangle is 30 in.
10 in.
10 in.
7. The perimeter of the
triangle is 15 cm.
8. The perimeter of the
triangle is 22 ft.
8 ft
5 cm
3 cm
euilateral
scalene
6 ft
isosceles
9. The angles of a triangular sail measure 90°, 30°, and 60°. Its
sides measure approximately 2 feet, 3.5 feet, and 4 feet.
Classify the triangular shape of the sail in two different ways.
It isle.
10. Two angles in one triangle are congruent to two angles in
another triangle. What can you conclude about the third angle
in both triangles?
ruent.
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Holt Mathematics
MSM07G6_RESBK_Ch08_095-117.pe
2/7/06
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Page 103
Puzzles, Twisters & Teasers
8-4 What is my Line?
Reading Strategies
8-4 Understanding Symbols
LESSON
LESSON
Use the figure on the right. For each box decide whether the
statement is true or false. If it is false, black out the box.
Parallel lines are the same distance apart and never meet.
The lines on a ruled piece of paper are
similar to parallel lines.
The symbol || stands for parallel.
A
C
E
G
I
K
Segment AB is parallel to segment CD.
This can be written: AB || CD.
B
D
F
H
J
L
"!#
FG ! "!#
HJ
A
"!#
FG ! "!#
GJ
G
"!#
HJ " "!#
FG
C
K
F
"!#
FH " "!#
GJ
B
"!#
FH ! "!#
HJ
W
"!#
FH " "!#
HJ
L
"!#
FG " "!#
FH
R
"!#
HJ ! "!#
GJ
S
"!#
GJ " "!#
KL
D
"!#
AD ! "!#
AG
E
"!#
BC & "!#
CD
are skew
P
"!#
DC " "!#
EF
G
1. Find another pair of parallel line segments in the figure above.
Possible answer: !
GH and !
IJ
G
H
J
L
2. Use the || symbol to write how the line segments are related.
!
GH || !
IJ
Perpendicular lines meet to form square corners.
T
Square
corner
The symbol ! stands for perpendicular. A square corner
is used as a symbol to indicate that two lines are
perpendicular to each other.
R
S
Q
TQ
!
!!!
RS
!
Read: segment TQ perpendicular to segment RS.
Use this figure to complete Exercises 3–5.
3. Segment BX is perpendicular to segment BO.
Write this with symbols.
B
C
A
B
O
X
Y
"!#
GF " "!#
AD
I
"!#
BH ! "!#
HE
O
"!#
BH " "!#
CE
M
"!#
HG " "!#
AB
O
"!#
HE ! "!#
CB
F
"!#
HG & "!#
BC
are skew
N
D
H
E
G
F
To solve the riddle, re-arrange the letters for the true boxes.
!
BX ! !
BO
4. Find two other line segments that are perpendicular to each
other.
eggonomics
What do hens study in college?
Possible answer: !
XY and !
OY
5. What symbol in the figure tells you that line segments are
perpendicular to each other?
the square corner
35
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Holt Mathematics
Practice A
8-5 Triangles
LESSON
Classify each triangle as acute, obtuse, or right.
2.
Use the diagram to find the measure of each indicated angle.
3.
60°
70°
90°
30°
60°
right
30°
50°
acute
5.
2 in.
2 in.
3 in.
6.
5 cm
5 cm
90°
2. "DAC
45°
120° 30°
3. "ABC
90°
4. "EBA
90°
5. "ACB
45°
4 ft
D
E
B
45°
45°
C
A
Classify each triangle using the given information.
6. The perimeter of the
triangle is 30 in.
5 ft
5 cm
1. "CBD
obtuse
Classify each triangle as scalene, isosceles, or equilateral.
4.
Holt Mathematics
Practice B
8-5 Triangles
LESSON
1.
36
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7. The perimeter of the
triangle is 15 cm.
8. The perimeter of the
triangle is 22 ft.
3 ft
isosceles
equilateral
scalene
10 in.
10 in.
8 ft
5 cm
Find the measure of the unknown angle.
7.
8.
?
90°
45°
45°
equilateral
35°
50°
?
?
70°
6 ft
3 cm
9.
60°
scalene
isosceles
9. The angles of a triangular sail measure 90°, 30°, and 60°. Its
sides measure approximately 2 feet, 3.5 feet, and 4 feet.
Classify the triangular shape of the sail in two different ways.
35°
110°
It is a right triangle; It is a scalene triangle.
10. One side of an equilateral triangle measures 4 cm. What are the
lengths of the other two sides of the triangle?
10. Two angles in one triangle are congruent to two angles in
another triangle. What can you conclude about the third angle
in both triangles?
They both measure 4 cm.
11. Karen says the angles of her triangle measure 90°, 50°, and
60°. Explain why this is impossible.
They are congruent.
The sum of those angles is 200°, and the sum of the angles in any
triangle is always 180°.
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
37
Copyright © by Holt, Rinehart and Winston.
Holt Mathematics
Copyright © by Holt, Rinehart and Winston.
All rights reserved.
103
38
Holt Mathematics
Holt Mathematics