UPSKILL MATH PLUS

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Area of circle:
The area of a circle is defined as the number of square units inside that circle. It is pi times the radius square. The degree of the circle is 360°.
 
Area of circle (A) =\pi r^2 square units, where π=3.14.
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Area of a semicircle:
The area of a semicircle is defined as the number of square units inside that circle. It is half(1/2pi times the radius square. The degree of the semicircle is 180°.
 
Area of a semicircle A=\frac{1}{2}\pi r^2 square units.
 
It can also be written as \frac{180^\circ}{360^\circ}\pi r^2 square units (where the degree of semicircle is 180^\circ).
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Area of one-third circle:
The area of one-third circle is defined as the number of square units inside that circle. It is one by three (1/3pi times the radius square. The degree of the one-third circle is 120°.
 
Are of a one - third of circle A=\frac{1}{3}\pi r^2 square units.
 
It can also be written as 120°360°πr2 square units (where the degree of sector is 120°).
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Area of quadrant circle:
The area of quadrant circle is defined as the number of square units inside that circle. It is one by quarter(1/4pi times the radius square. The degree of the quadrant circle is 90°.
 
Area of a quadrant circle A=\frac{1}{4}\pi r^2 square units.
 
It can also be written as 90°360°πr2 square units (where the degree of quadrant circle is 90°).
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From the above explanation, we get the idea that the area of a sector is equal to the number of square units inside that circle. It is pi time the radius square by θ°360° where θ=360°n.
Therefore the area of the sector of the circle A=θ°360°×πr2 square units.
Important!
If a circle of radius(r) units divided into n equal sectors, then the
area of the sector = \frac{1}{n}\times \pi r^2 square units.