How to Find the Area of Sectors

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How to Find the Area of Sectors
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Lets begin with a review of finding the area of
a circle.
4 ft
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Arearadius x radius x p
4 ft
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Area4 ft x 4 ft x p
4 ft
5
Area4 ft x 4 ft x 3.14
4 ft
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Area4 ft x 4 ft x 3.14
50.24 ft2
4 ft
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A sector is a piece of the circle, like a slice
of pie.
¾ of a circle
½ of a circle
¼ of a circle
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You can find the area of each sector by finding
the area of the whole circle
3 m
3 m
3 m
3 m
¾ of a circle
½ of a circle
¼ of a circle
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You can find the area of each sector by finding
the area of the whole circle
3 m
3 x 3 x 3.14 28.26 m2
3 m
3 m
3 m
¾ of a circle
½ of a circle
¼ of a circle
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then multiply by the fraction.
3 m
3 x 3 x 3.14 28.26 m2
¾ of 28.26 m2
3 m
¾ of a circle
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then multiply by the fraction.
3 m
3 x 3 x 3.14 28.26 m2
¾ of 28.26 m2
3 m
¾ x 28.26 m2 21.195 m2
¾ of a circle
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then multiply by the fraction.
3 m
3 x 3 x 3.14 28.26 m2
½ of 28.26 m2
3 m
½ of a circle
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then multiply by the fraction.
3 m
3 x 3 x 3.14 28.26 m2
½ of 28.26 m2
3 m
½ x 28.26 m2 14.13 m2
½ of a circle
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then multiply by the fraction.
3 m
3 x 3 x 3.14 28.26 m2
¼ of 28.26 m2
3 m
¼ of a circle
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then multiply by the fraction.
3 m
3 x 3 x 3.14 28.26 m2
¼ of 28.26 m2
3 m
¼ x 28.26 m2 7.065 m2
¼ of a circle
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Practice Time!
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1) Find the area of the sector.
5 m
¼ of a circle
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1) Find the area of the sector.
First find the area of the whole circle with a
radius of 5 m.
5 m
5 m
¼ of a circle
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1) Find the area of the sector.
First find the area of the whole circle with a
radius of 5 m.
Now, find the ¼ of the whole area.
5 m
5 m
¼ of a circle
5 x 5 x 3.14 78.5 m2
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1) Find the area of the sector.
First find the area of the whole circle with a
radius of 5 m.
Now, find the ¼ of the whole area.
5 m
5 m
¼ of 78.5 m2
5 x 5 x 3.14 78.5 m2
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1) Find the area of the sector.
First find the area of the whole circle with a
radius of 5 m.
Now, find the ¼ of the whole area.
5 m
5 m
¼ of 78.5 m2
5 x 5 x 3.14 78.5 m2
¼ x 78.5 m2 19.625m2
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1) Find the area of the sector.
First find the area of the whole circle with a
radius of 5 m.
Now, find the ¼ of the whole area.
5 m
5 m
¼ of 78.5 m2
5 x 5 x 3.14 78.5 m2
¼ x 78.5 m2 19.625m2
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2) Find the area of the sector.
6 m
1/3 of a circle
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2) Find the area of the sector.
First find the area of the whole circle with a
radius of 6 m.
6 m
6 m
1/3 of a circle
6 x 6 x 3.14 113.04 m2
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2) Find the area of the sector.
First find the area of the whole circle with a
radius of 6 m.
Now, find the 1/3 of the whole area.
6 m
6 m
1/3 of 113.04 m2
6 x 6 x 3.14 113.04 m2
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2) Find the area of the sector.
First find the area of the whole circle with a
radius of 6 m.
Now, find the 1/3 of the whole area.
6 m
6 m
1/3 of 113.04 m2
6 x 6 x 3.14 113.04 m2
1/3 x 113.04 m2 37.68 m2
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3) Find the area of the sector.
8 m
4/5 of a circle
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3) Find the area of the sector.
First find the area of the whole circle with a
radius of 8 m.
8 m
8 m
4/5 of a circle
8 x 8 x 3.14 200.96 m2
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3) Find the area of the sector.
First find the area of the whole circle with a
radius of 8 m.
Now, find the 4/5 of the whole area.
8 m
8 m
4/5 of a circle
8 x 8 x 3.14 200.96 m2
4/5 x 200.96 m2 160.768 m2
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4) Find the area of the sector.
10 m
2/3 of a circle
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4) Find the area of the sector.
First find the area of the whole circle with a
radius of 10 m.
10 m
10 m
2/3 of a circle
10 x 10 x 3.14 314 m2
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4) Find the area of the sector.
First find the area of the whole circle with a
radius of 10 m.
Now, find the 2/3 of the whole area.
10 m
10 m
2/3 of a circle
10 x 10 x 3.14 314 m2
2/3 x 314 m2 209.3 m2
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5) Find the area of the sector.
6 m
7 m
120
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5) Find the area of the sector.
First find the area of the whole circle with a
radius of 7 m.
6 m
7 m
7 m
120
7 x 7 x 3.14 153.86 m2
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5) Find the area of the sector.
First find the area of the whole circle with a
radius of 7 m.
Now, find the 120/360 of the whole area.
6 m
7 m
7 m
120
120/360 of a circle
7 x 7 x 3.14 153.86 m2
120/360 x 153.86 m2 51.286 m2
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6) Find the area of the sector.
6 m
9 m
45
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6) Find the area of the sector.
First find the area of the whole circle with a
radius of 9 m.
6 m
9 m
9 m
45
9 x 9 x 3.14 254.34 m2
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6) Find the area of the sector.
First find the area of the whole circle with a
radius of 9 m.
Now, find the 45/360 of the whole area.
6 m
9 m
9 m
45
45/360 of a circle
9 x 9 x 3.14 254.34 m2
45/360 x 254.34 m2 31.7925 m2
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The End