Question 22

If the perimeter of a semicircle is 72 cm, then ﬁnd its area $$(in cm^2)$$.

Solution

Let radius of semi circle = $$r$$ cm

=> Perimeter of semi circle = $$\pi r+2r=72$$

=> $$r(\frac{22}{7}+2)=72$$

=> $$r(\frac{22+14}{7})=72$$

=> $$r=72\times\frac{7}{36}=14$$ cm

$$\therefore$$ Area of semi-circle = $$\frac{1}{2} \pi r^2$$

= $$\frac{1}{2}\times\frac{22}{7}\times(14)^2$$

= $$22\times14=308$$ $$cm^2$$

=> Ans - (A)

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