Transcript Slide 1

10-3 Area of Parallelograms
Warm Up
Find each product.
1. 8  12
96
2. 3 1  5 1
56
or 18 2
3
3
2
3
3. 9.4  6.3
59.22
4. 3.5  7
24.5
Holt CA Course 1
10-3 Area of Parallelograms
California
Standards
AF3.1 Use variables in expressions
describing geometric quantities (e.g.,
P = 2w + 2l, A = 12bh, C = pd–the formulas
for the perimeter of a rectangle, the area of
a triangle, and the circumference of a circle,
respectively).
Also covered: NS2.1,
AF1.1,
AF2.1, AF3.2
Holt CA Course 1
10-3 Area of Parallelograms
Vocabulary
area
base
height
Holt CA Course 1
10-3 Area of Parallelograms
The area of a figure is the number
of non-overlapping unit squares
needed to cover the figure. Area is
measured in square units.
Area = 15 square units
The base of a parallelogram is the length of
one side.
Its height is the perpendicular distance from
the base to the opposite side.
h
b
Holt CA Course 1
10-3 Area of Parallelograms
Holt CA Course 1
10-3 Area of Parallelograms
Finding the Area of a Parallelogram
Find the area of the parallelogram.
A = bh
8m
16 m
Use the formula.
A = 16· 8 Substitute for b and h.
A = 128
Multiply.
The area of the parallelogram is 128 m2.
Holt CA Course 1
10-3 Area of Parallelograms
Find the area of the parallelogram.
A = bh
6 cm
12 cm
Use the formula.
A = 12· 6 Substitute for b and h.
A = 72
Multiply.
The area of the parallelogram is 72 cm2.
Holt CA Course 1
10-3 Area of Parallelograms
Find the area of the rectangle.
4.5 in.
7.4 in.
A = lw
A = 7.4 · 4.5
A = 33.3
Use the formula.
Substitute for l and w.
Multiply.
The area of the rectangle is 33.3 in2.
Holt CA Course 1
10-3 Area of Parallelograms
Find the area of the rectangle.
6.3 in.
8.2 in.
A = lw
A = 8.2 · 6.3
A = 51.66
Use the formula.
Substitute for l and w.
Multiply.
The area of the rectangle is 51.66 in2.
Holt CA Course 1
10-3 Area of Parallelograms
The area of a playing field is 1,470 ft2 and the
length is 42 ft. What is the width of the field?
A = lw
1,470 = 42 · w
1,470 = 42 · w
42
42
35 = w
Use the formula for the area of a
rectangle.
Substitute 1,470 for A and 42 for l.
Divide both sides by 42 to isolate w.
The width of the playing field is 35 ft.
Holt CA Course 1
10-3 Area of Parallelograms
The area of a rectangular parking lot is
3,570 ft2 and the width is 70 ft. What is the
length of the parking lot?
A = lw
3,570 = l · 70
3,570 = l · 70
70
70
51 = l
Use the formula for the area of a
rectangle.
Substitute 3,570 for A and 70 for w.
Divide both sides by 70 to isolate l.
The length of the parking lot is 51 ft.
Holt CA Course 1
10-3 Area of Parallelograms
A carpenter is laying a wood floor measuring
4 yd by 5 yd. How many square feet of
flooring material does she need?
4 yd
Step 1: Convert yards to feet.
5 yd
Step 2: Solve.
A=lw
A= 4 (3) x 5 (3)
A= 12 x 15
The carpenter needs 180 ft2 of flooring material.
Holt CA Course 1
10-3 Area of Parallelograms
A carpenter is laying a tile floor measuring 5
yd by 7 yd. How many square feet of tile
material does she need?
5 yd
L x W= A
7 yd
7 (3) x 5 (3) = A
21 x 15 = A
The carpenter needs 315 ft2 of tile material.
Holt CA Course 1
10-3 Area of Parallelograms
Lesson Quiz: Part I
Find the area of each figure.
1.
2.
24.5 ft2
4.
Holt CA Course 1
57 =
2
28 1 ft2
2
105
1
or 13 in2
8
8