Question

if the diameter of a circle is 70 cm,find the area and perimeter of the semicircle.

Answer 1

diameter of circle = 2r
now, 2r=70 cm (given)
=> r=35 cm
Area of Semicircle = πr²/2 = 1924.225 cm²
Perimeter of semicircle = πr+2r = r(π+2)
= 179.956 cm

Answer 2

$Perimeter \: of \: a \: semi \: circle = \frac{\pi \: d}{2}$
$= \frac{22}{7} \times 70 \times \frac{1}{2}$
$\frac{220}{2} = 110 \: cm$

$area \: of \: semi circle = \pi {r}^{2}\times \frac{1}{2}$

$diameter = 70 \: or \: radius = 140$

$= \frac{22}{7} \times 140 \times 140\times \frac{1}{2}$
$= 22 \times 140$
$= 308 \: {cm}^{2}$