Question

work out the area and the perimeter of each semicirlce
give your answers correct to one decimal place

a) radius=12.5
b) diameter=46mm

Answer 1

$\large\bold{\sf{Solution \rightarrow}}$

$\large\underline{\sf{given \rightarrow radius \rightarrow 12.5cm}}$

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$\large\underline{\sf{to \: find:area \: and \: perimeter}}$

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$\large\underline{\sf{formula \: used \downarrow}}$

$\large\underline{\sf{perimeter \rightarrow \pi r}}$

$\large\underline{\sf{area \rightarrow \frac{\pi {r}^{2} }{2} }}$

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$\large\underline{\sf{ perimeter_{semicircle} \rightarrow \frac{22}{7} \times 12.5 }}$

$\large\underline{\sf{perimeter \rightarrow 39.28cm}}$

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$\large\underline{\sf{ area_{semicircle} \rightarrow \frac{\pi {12.5}^{2} }{2} }}$

$\implies \frac{22 \times 12.5}{7 \times 2}$

$\implies \large\underline{\sf{19.64 {cm}^{2} }}$

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2.=>

$\large\underline{\sf{ perimeter_{semicircle} = \frac{\pi d}{2} }}$

=> 22×46/7×2

=>72.28

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Area=πr²/2

Area=22×23×23/7×2

==>831.28