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Question
Find the area and perimeter of the following semicircles: Diameter = 7cm
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Solution
The radius of a Circle with diameter d is r = `"d"/(2)`
The Area of a Semi-circle with radius r = `(pi"r"^2)/(2)`
The Perimeter of a Semi-circle with radius r
= πr + 2r
= r(π + 2)
= `"r"(22/7 + 2)`
= `(36)/(7) xx "r"`
The radius of a Circle with diameter 7 is r
= `(7)/(2)`
= 3.5cm
The Area of a Semi-circle with radius 3.5
= `(pi(3.5)^2)/(2)`
= 19.25cm2
The Perimeter of a Semi-circle with radius r
= π x 3.5 + 2 x 3.5
= 3.5(π + 2)
= `3.5(22/7 + 2)`
= `(36)/(7) xx 3.5`
= 25cm.
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