Facts about Area of Shapes Dr. Kent Bryant 5/2011.
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Transcript of Facts about Area of Shapes Dr. Kent Bryant 5/2011.
![Page 1: Facts about Area of Shapes Dr. Kent Bryant 5/2011.](https://reader036.fdocuments.us/reader036/viewer/2022082517/56649e315503460f94b225a2/html5/thumbnails/1.jpg)
Facts about Area of Shapes
Dr. Kent Bryant5/2011
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SQUARE
IF A SQUARE HAS SIDES WITH LENGTH L THEN
AREA = L X L
EG. WHAT IS THE AREA OF A SQUARE WITH LENGTH 20 cm?
Area = 20 cm X 20 cm = 400 cm2
L
L
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RECTANGLE
L
W
IF A RECTANGLE HAS LENGTH L AND WIDTH W
A = L X W
EG. WHAT IS THE AREA OF A RECTANGLE WITH LENGTH 20cm AND WIDTH 40cm?
Area =20 cm x 40 cm = 800 cm2
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Triangle
H
BIF A TRIANGLE HAS HEIGHT H AND BASE B
AREA = ½ B X H
EG. WHAT IS THE AREA OF A TRIANGLE WITH HEIGHT 20 cm AND BASE 15 cm?
Area = ½ x 20 x 15 – 150 cm2
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Circumference of a Circle
The circumference of a circle is the distance around the circle
Circumference = Diameter X π (C = π d) π = 3.14Circumference = 2πr (r = radius)
What is the circumference of a circle with radius 5 cm?
C = 2πr = 2 X 3.14 X 5 = 31.4 cm
The diameter of a circle is the distance across the circle through the center point.
The radius of a circle is the distance from the center to the outer edge of the circle.
Diameter = 2 X radius
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Area of a Circle
If a circle has a radius R then
Area = π R2
Eg. What is the area of a circle with radius 10 cm?
Area = 3.14 X 10 X 10 = 314 cm2
R
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Area of Parallelogram
B
B
H
If a Parallelogram has height H and a base length of B then
Area -= B X H
Eg. What is the area of a Parallelogram with Height 10 cm and Base length 20cm?
Area – B X H = 20 cm X 10 cm =200 cm2
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What about Irregular Shapes?
How do you find the area of this shape?
First – Break shape into smaller REGULAR shapes.
In this case a rectangle and two triangles.
Now find the area of these smaller shapes.
Add all three areas together to get your answer.
![Page 9: Facts about Area of Shapes Dr. Kent Bryant 5/2011.](https://reader036.fdocuments.us/reader036/viewer/2022082517/56649e315503460f94b225a2/html5/thumbnails/9.jpg)
What about Irregular Shapes?
How do you find the area of this shape?
First – Break shape into smaller REGULAR shapes.
In this case five rectangles.
Now find the area of these smaller shapes.
Add all five areas together to get your answer.