Question 38

What is the perimeter of the sector whose central angle is 60° and radius of the circle is 21 cm?

Solution

Central angle = $$\theta = 60$$° and radius = $$r = 21$$ cm

Perimeter of sector = length of arc + (2$$\times$$ radius)

Length of arc = $$\frac{\theta}{360} \times 2 \pi r$$

= $$\frac{60}{360} \times 2 \times \frac{22}{7} \times 21$$

= $$\frac{1}{6} \times 44 \times 3 = \frac{44}{2} = 22$$ cm

$$\therefore$$ Perimeter of sector = $$22 + (2\times 21)$$

= $$22+42=64$$ cm

=> Ans - (C)

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