Question

Find the area and perimeter of the following semicircles: Diameter = 7cm

Answer 1

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.