All the solutions provided in McGraw Hill My Math Grade 3 Answer Key PDF Chapter 13 Review will give you a clear idea of the concepts.
McGraw-Hill My Math Grade 3 Chapter 13 Review Answer Key
Vocabulary Check
Use the word bank to complete each sentence.
area
composite figure
formula
perimeter
square unit
unit square
Question 1.
The distance around the outside of a figure is its ______________.
Answer: The distance around the outside of a figure is its perimeter.
Question 2.
A unit square has one _______________ of area and can be used to measure area.
Answer: A unit square has one square unit of area and can be used to measure area.
Question 3.
A _______________ is an equation that shows the relationship between two or more quantities.
Answer: A formula is an equation that shows the relationship between two or more quantities.
Question 4.
_______________ is the number of square units needed to cover a figure without overlapping.
Answer: area is the number of square units needed to cover a figure without overlapping.
Question 5.
A square with aside length of one unit is called a _______________.
Answer: A square with aside length of one unit is called a unit square
Question 6.
A _______________ is made up of two or more figures.
Answer: A composite figure is made up of two or more figures.
Concept Check
Estimate the perimeter of each figure ¡n centimeters. Then measure the perimeter to the nearest centimeter.
Question 7.
Estimate: _______________
Actual: _________________
Answer:
Esimated perimeter is 10.
P = 3 + 3 + 2 = 8 cm
So, the actual perimeter is 8 centimeters.
Question 8.
Estimate: _______________
Actual: _________________
Answer:
Esimated perimeter is 10.
P = 2 + 2 + 4 + 4 = 12 cm
So, the actual perimeter is 12 centimeters.
Find the perimeter of each figure.
Question 9.
Answer:
P = 3 + 6 + 4 = 13 cm
So, the perimeter of the given figure is 13 cm.
Question 10.
Answer:
P = 4 + 4 + 4 + 4 + 4 + 4 = 24 ft
So, the perimeter of the given figure is 24 ft.
Algebra Find the unknown side length for each figure. The perimeter of each figure is 30 meters.
Question 11.
The unknown is _____________ meters.
Answer:
P = 30m
L = 10m
W = x
P = 2L + 2W
30 = 2(10) + 2W
30 – 20 = 2W
2W = 10
W = 10/2 = 5 meters
Question 12.
The unknown is _____________ meters.
Answer:
P = 30m
s = 6
P = 5s
30 = 5s
s = 30/5
s = 6
So, the unknown is 6 meters.
Algebra Count unit squares to find the area of each figure. Then write a multiplication equation.
Question 13.
Area: _______________
Equation: ______________
Answer:
L = 5
W = 2
Area of the rectangle = lw
A = 5 × 2 = 10 sq. units
Question 14.
Area: _______________
Equation: ______________
Answer:
l = 3
w = 4
Area of the rectangle = lw
A = 3 × 4 = 12 sq. units
Find the area of each rectangle.
Question 15.
______________ square inches
Answer:
l = 6 in.
w = 4 in.
Area of the rectangle = lw
A = 6 × 4 = 24 sq. in.
Question 16.
______________ square inches
Answer:
l = 9m
w = 5m
Area of the rectangle = lw
A = 9 × 5 = 45 sq. meters
Problem Solving
Refer to the figure at the right for Exercises 17-18. The figure represents Kathleen’s backyard.
Question 17.
Use the Distributive Property to find the area of Kathleen’s backyard.
Answer:
l = 12m
w = 5m
Area of the rectangle = lw
A = 12 × 5
= (6 × 5) + (6 × 5)
= 30 +30
= 60 sq. meters
Question 18.
Tile the rectangle to find its area. What do you notice?
Answer:
l = 3
w = 4
Area = 3 × 4 = 12 sq. units
For Exercises 19 through 21, refer to the figure at the right. The figure shows the shape of a room. Each unit square represents 1 square foot.
Question 19.
What is the area of the room in square feet?
Answer:
Figure 1:
l = 4
w = 2
Area = 4 × 2 = 8 sq. ft
Figure 2:
l = 2
w = 4
Area = 2 × 4 = 8 sq. ft
So, the area of the room in square feet is 8 + 8 = 16 sq. ft
Question 20.
What is the perimeter of the room in feet?
Answer:
Figure 1:
l = 4
w = 2
P = 2(l + w)
P = 2(4 + 2)
P = 12 ft
Figure 1:
l = 4
w = 2
P = 2(l + w)
P = 2(4 + 2)
P = 12 ft
So, the perimeter of the room in feet is 12 + 12 = 24 ft
Question 21.
Decompose the figure into two rectangles to find its area. What do you notice?
Answer:
To decompose is to separate into two or more parts. In the above question we have divided the figure into two parts and then find the area of the room.
Test Practice
Question 22.
Find the unknown side length of the figure to the right. The perimeter is 26 inches.
(A) 5 inches
(B) 8 inches
(C) 9 inches
(D) 10 inches
Answer: (B) 8 inches
Explanation:
L = 8
W = 5
Opposite sides are equal in the rectangle.
So, option B is the correct answer.
Reflect
Use what you learned about perimeter and area to complete the graphic organizer.
Now reflect on the ESSENTIAL QUESTION Write your answer below.
Answer:
