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Area & Perimeter of Parallelograms
w
l
The distance around a geometric figure is its perimeter. To find the perimeter P of a polygon, you can add the lengths of its sides.
Rectangle P = 2l + 2w
Square P = 4l
l
Parallelogram P = 2l + 2w
l
w
l
Find the perimeter.
36 in.
45 m
8 m12 m
9 m6 m
10 m 8 in.
10 in.
Ex1)
If a fence is to be placed around a
rectangular playground with a length of 21 ft
and a width of 30 ft how many feet of fence
is needed.
Ex2)
102 ft
A = lw w
l
The area of a figure is the number of unit squares needed to cover the figure. Area is measured in square units.
Rectangle
Square A = l 2 =
l
Parallelogram
l
A = bh b
h
A = bh h
b
l●l
Parallelograms have the same area formula as rectangles . If you cut the parallelogram to form a 90 degree angle on one sided and replace it on the other side of parallelogram you form a rectangle. The area is the same amount.
Not in notes
Find the area.
4.5 in.
7.4 in.
A = lw
A = 7.4 · 4.5
A = 33.3 in
Use the formula.
Substitute for l and w.
Multiply.
Ex3)
8 m
16 m
A = bh
A = 16· 8
A = 128 m
Ex4)
A = bh
A = 12· 6
A = 72 ft
8 ft
12 ft
Ex5)6 ft
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
= · 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.1,47042
4242
35 = w
Ex6)
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
= · w
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 w.3,57070
7070
51 = l
Ex7)
notes
Area & Perimeter of Parallelograms
Date __________
The ______________a geometric figure is its perimeter. To find the perimeter P of a polygon, you can add the lengths of its sides.
Rectangle
Square
Parallelogram
Find the perimeter.
8 m12 m
9 m6 m
10 m 8 in.
10 in.
Ex1)
If a fence is to be placed around a
rectangular playground with a length of 21 ft
and a width of 30 ft how many feet of fence
is needed.
Ex2)
The area of a figure is the number _____________ needed to _____ the figure. Area is measured in square units.
Rectangle
Square
Parallelogram
Find the area.
4.5 in.
7.4 in.
Ex3)
8 m
16 m
Ex4)
· 6
8 ft
12 ft
Ex5)6 ft
The area of a playing field is 1,470 ft2 and the length is 42 ft. What is the width of the field?
Ex6)
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?
Ex7)
