Question

a 7. The perimeter of a semicircle is 108 cm. What is the area of the semicircle ? (1) 636 cm (2) 693 cm (3) 1272 cm (4) 1386 cm​

Answer 1

Perimeter = 108 cm

So, r(2 + π) = 108

$\sf \: r(2 + \frac{22}{7} ) = 108$

$\sf \: r \: x \: \frac{36}{7} =108$

$\sf \: r=108 \: x \: 7/36$

$\sf \: r=21 cm$

$\sf \: Area \: of \: semicircle= \frac{πr^2}{2}$

$\sf \: 22/7 \: x \: 21 \: x \: \frac{21}{2}$

$\sf= 22 \: x \: 3 \: x \: \frac{21}{2}$

$\sf \: =11 \: x \: 3 \: x \: 21$

$\sf \: {693} \: cm^{2}$

Hope it helps!

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