10.1 Area of Rectangles and Parallelograms

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10.1 Area of
Rectangles and
Parallelograms
I can find the area of rectangles and
parallelograms
Area Rap
Warm Up
1. What is the perimeter of a square with side
60 in.
lengths of 15 in.?
2. What is the perimeter of a rectangle with
length 16 cm and width 11 cm?
54 cm
The area of a figure is the amount
of surface it covers. We measure
area in square units.
Find the area of the figure.
15 in.
A = lw
9 in.
The area is about 135 in2.
Find the area of the figure.
13 in.
A = lw
7 in.
The area is about 91 in2.
You can use the formula for the area of a rectangle
to write a formula for the area of a parallelogram.
Imagine cutting off the triangle drawn in the
parallelogram and sliding it to the right to form a
rectangle.
The area of a parallelogram = bh.
The area of a rectangle = lw.
The base of the parallelogram is the length of the
rectangle. The height of the parallelogram is the
width of the rectangle.
Find the area of the parallelogram.
A = bh
1 1 ft
4
2 1 ft
2
25
1
___
__
A=
or 3
8
8
1 2
__
The area is 3 ft .
8
Find the area of the parallelogram.
3 1 ft
2
A = bh
1 1 ft
2
21
1
A = ___ or 5 __
4
4
1 2
__
The area is 5 4 ft .
Jessica is going to tile a kitchen that measures
13 ft by 17 ft. Some floor space is taken up by
an island that measures 3 ft by 6 ft. How much
area remains to be tiled in the kitchen?
The area of the kitchen to be tiled is 203 ft2.
Miguel is going to landscape his backyard that
measures 16 ft by 11 ft. Some of the backyard
space is taken up by a built-in BBQ that
measures 2 ft by 4 ft. How much area remains
to be landscaped?
The area of the backyard to be landscaped is 168 ft2.
Lesson Quiz
Find the area of each figure.
1.
2.
41.4 m2
48 ft2
3. What is the area of a parallelogram with base 16
160 in2
in. and height 10 in.?
4. A square fish pond that is 6 ft long is
surrounded by a square walk that is 18 ft long.
What is the area covered by the walk?
288 ft2
10.2 Area of Triangle
and Trapezoids
I can find the area of triangles and
trapezoid
You can divide any parallelogram into two
congruent triangles. So the area of each triangle
is half the area of the parallelogram.
Find the area of the triangle.
A = 1 bh
2
A = 120
The area is 120 ft2.
Find the area of the triangle.
A = 1 bh
2
A = 360
The area is 360 in2.
12 cm
Find the area of the trapezoid.
7 cm
A = 1 h(b1 + b2)
2
A = 98
The area is 98 cm2.
16 cm
Lesson Quiz
Find the area of each triangle.
1.
39.9 cm2
2.
Find the area of each trapezoid.
3.
4.
22.5 m2
84 mi2
113
3 2
in
4

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