In a circle of diameter 42cm ,if an arc subtends an angle of 60 ˚ at the centre where ``\pi`=`22/7`,then the length of the arc is

(a) 22/7 cm

(b) 22 cm

(c) 44 cm

(d) 11cm

(b) 22 cm

**Explanation:**

Length of Arc APB = `\frac{\theta}{360}``\times``(2\pi "r")`

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

= `1/6` `\times` 2`\times` `22/7` `\times` 21

= 22 cm