Question

what is the area of a semicircle whose dia is 20 cm (d)

Answer 1

$\underline{\textsf{Given:}}$

$\textsf{Diameter of semi circle is 20 cm}$

$\underline{\textsf{To find:}}$

$\textsf{Area of the semi circle}$

$\underline{\textsf{Solution:}}$

$\mathsf{Diameter=20\;cm}$

$\mathsf{Radius\;of\;the\;semi\;circle,\,r=\dfrac{Diameter}{2}}$

$\mathsf{=\dfrac{20}{2}}$

$\mathsf{=10\;cm}$

$\mathsf{Now,}$

$\mathsf{Area\;of\;the\;semi\;circle}$

$\mathsf{=\dfrac{\pi\,r^2}{2}}$

$\mathsf{=\dfrac{3.14{\times}10{\times}10}{2}}$

$\mathsf{=3.14{\times}10{\times}5}$

$\mathsf{=31.4{\times}5}$

$\mathsf{=157\;square\;cm}$

$\underline{\textsf{Answer:}}$

$\textsf{Area of the semi circle is 157 square cm}$

$\underline{\textsf{Find more:}}$

The radius of a circle is 8cm determine the radius of another circle whose area is 16times more than the first circle​

https://brainly.in/question/16983428

Answer 2

Given,

• Diameter of semicircle = 20 cm
• Radius of semicircle = 20/2 cm

We know,

$\text{Area of semicircle} = \frac{ \text{Area of circle}}{2} \\ \\ = > \text{Area of semicircle} = \green{ \frac{\pi {r}^2}{2} }$

Here,

$\text{Area of semicircle} = \frac{\pi \times {\big(\frac{20}{2}\big) }^2}{2} \\ \\ = > \frac{\pi \times {(10)}^2}{2}= \frac{3.14 \times 100 }{2} \: \: \: \: \: \{ \text{using \:}{ \pi }{ = 3.14\: \: } \}\\ = > (3.14 \times 50) \: \: \rm {cm}^{2} \\ => 157 \: \: \text{cm² }$

Thus,

• A semicircle whose diameter is 20 cm will have area of 157 cm²