Question 22

If the perimeter of a semi-circle is 108 cm, then find its radius (in cm).

Solution

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

=> Perimeter of semi circle = $$\pi r+2r=108$$

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

=> $$r(\frac{22+14}{7})=108$$

=> $$r=108\times\frac{7}{36}$$

=> $$r=3\times7=21$$ cm

=> Ans - (D)

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