Question

Find the length of the arc which subtends ${120}^o$ angle at centre of circle whose radius is 21 cm.

• A. 11 cm
• B. 44 cm
• C. 22 cm
• D. 88 cm

Answer 1

The correct option is B 44 cm

Length of arc = $\frac{Angle}{{360}^o}\times 2\pi r$
Considering the value of $\pi$ as $\frac{22}{7}$,
length of the arc = $\frac{{120}^o}{{360}^o}\times 2\times \frac{22}{7}\times 21$
= $\frac{1}{3}\times 2\times \frac{22}{7}\times 21$
= $44cm$