Cha
p
Name:
Date:
ter
Area of a Triangle
Practice 1 Base and Height of a Triangle
Complete to give both the base and the height in each triangle.
Example
C
A
© 2009 Marshall Cavendish International (Singapore) Private Limited
height
Height:
Base:
B
W
1.
BA
AC
A
2.
he
igh
t
V
T
Y
X
B
C
Z
U
base
Height:
Base:
Base:
Height:
3.
T
4.
D
base
A
C
e
bas
V
E
S
Base:
Height:
U
W
B
Base:
Height:
Lesson 6.1 Base and Height of a Triangle
G5_WB_Ch06.indd 197
197
1/12/09 6:26:11 PM
For each triangle, the base is given. Label the height.
Use a drawing triangle to draw the height.
Example
base
height
ba
6.
se
base
7.
8.
base
base
9.
10.
base
198
G5_WB_Ch06.indd 198
© 2009 Marshall Cavendish International (Singapore) Private Limited
5.
base
Chapter 6 Area of a Triangle
1/15/09 4:51:51 PM
Name:
Date:
Practice 2
Finding the Area of a Triangle
Find the area of each shaded triangle. Show each step and
give your answer using the correct units.
Example
23 cm
© 2009 Marshall Cavendish International (Singapore) Private Limited
15 cm
1 × 23 × 15
Area of triangle 2
172 1 cm2
2
1.
26 m
17 m
2.
54 cm
72 cm
3.
70 ft
45 ft
32 ft
Lesson 6.2
G5_WB_Ch06.indd 199
Finding the Area of a Triangle
199
1/12/09 6:26:15 PM
Find the area of each shaded triangle.
Example
4.
8 cm
9 in.
6 cm
10 cm
4 in.
12 in.
1 ×8×6
Area 2
24 cm2
in.
5 cm
25
18 in.
5 cm
Area Area © 2009 Marshall Cavendish International (Singapore) Private Limited
6.
28 in.
6 cm
5.
Area 8.
7.
25 in.
4 in.
7 in.
5 in
15 in.
.
6 in.
20 in.
200
G5_WB_Ch06.indd 200
Area Area Chapter 6 Area of a Triangle
1/12/09 6:26:16 PM
Name:
1.
Date:
Four students found the area of the shaded triangle.
3 cm
4 cm
cm
4 cm
5
These are their findings.
© 2009 Marshall Cavendish International (Singapore) Private Limited
Zach: 4 4 16 cm2
1
Preeti: 2 5 4 10 cm2
1
Brian: 2 7 4 14 cm2
1
James: 2 3 4 6 cm2
Explain the mistakes they have made. Then write the correct answer.
Zach:
Preeti:
Brian:
James:
The area of the shaded triangle is:
Chapter 6 Area of a Triangle
G5_WB_Ch06.indd 201
201
1/12/09 6:26:19 PM
3.
ABCD is a rectangle and BE EC.
A
4 cm
D
3 cm
B
2 cm
E
2 cm C
© 2009 Marshall Cavendish International (Singapore) Private Limited
The area of the shaded triangle is 15 cm2.
Explain why the area of the rectangle is 30 cm2.
2.
What can you say about the areas of triangles BED and ECD?
Explain your answer.
202
G5_WB_Ch06.indd 202
Chapter 6 Area of a Triangle
1/12/09 6:26:20 PM
Name:
Date:
Put On Your Thinking Cap!
Challenging Practice
Solve. Show your work.
1.
ABCD is a square of side 10 cm and BE EC.
Find the area of the shaded triangle.
10 cm
© 2009 Marshall Cavendish International (Singapore) Private Limited
B
2.
ABCD is a rectangle 18 cm by 8 cm.
AE ED and AF FB. Find the area
of the shaded triangle.
D
A
A
E
C
E
D
F
8 cm
B
18 cm
C
Chapter 6 Area of a Triangle
G5_WB_Ch06.indd 203
203
1/12/09 6:26:20 PM
BCD is a rectangle of area 48 square inches.
A
The length of CD is 3 times the length of DF.
BC 5 4 in.
a. Find the length of DF.
b. Find the area of the shaded triangle.
4.
ABCD is a rectangle 12 cm by 5 cm.
BE 5 4 cm. Find the area of the
shaded region, ABED.
A
D
A
G5_WB_Ch06.indd 204
B
F
12 cm
C
D
5 cm
B 4 cm E
204
E
C
© 2009 Marshall Cavendish International (Singapore) Private Limited
3.
Chapter 6 Area of a Triangle
10/23/09 10:16:08 AM
Name:
5.
Date:
The side of square ABCD is 8 cm. AE AF 4 cm.
Find the area of the shaded triangle, CEF.
A
E
D
B
8 cm
C
4 cm
© 2009 Marshall Cavendish International (Singapore) Private Limited
F
6.
The perimeter of rectangle ABCD is 256 inches. Its length is 3
times as long as its width. Find the area of triangle ABC.
A
D
B
C
Chapter 6 Area of a Triangle
G5_WB_Ch06.indd 205
205
1/12/09 6:26:22 PM
ABCD is a rectangle of area 72 square centimeters.
The length of AD is 3 times the length of AE.
BF 8 cm.
a.
A
Find the width of the rectangle.
E
B
b.
206
G5_WB_Ch06.indd 206
D
F
C
Find the area of the shaded region, EBFD.
© 2009 Marshall Cavendish International (Singapore) Private Limited
7.
Chapter 6 Area of a Triangle
1/12/09 6:26:23 PM
Name:
Date:
Put On Your Thinking Cap!
Problem Solving
Look at the pattern of these triangles.
1.
© 2009 Marshall Cavendish International (Singapore) Private Limited
16 cm
8 cm
4 cm
2 cm
2 cm
4 cm
8 cm
Triangle 1
Triangle 2
Triangle 3
16 cm
Triangle 4
What is the area of Triangle 5 in the pattern?
Which triangle in the pattern will have an area of 32,768 cm2?
Chapter 6 Area of a Triangle
G5_WB_Ch06.indd 207
207
1/12/09 6:26:23 PM
2.
ABCD is a square with sides of 20 cm. AX XB, BY YC, CZ ZD,
AW WD. WY and XZ are straight lines. Find the total area of the
shaded parts.
A
W
X
Z
Y
C
© 2009 Marshall Cavendish International (Singapore) Private Limited
B
D
208
G5_WB_Ch06.indd 208
Chapter 6 Area of a Triangle
1/15/09 4:51:56 PM