What is the perimeter of the sector with radius 10.5 cm and sector angle 60°? 

Given that, 

Radius of sector is 10.5 cm  

Also sector angle 60° 

Perimeter of the sector $= 2r +\frac{2\Pi r \theta }{360° }$

$$= 2\times 10.5 + \left(\frac{2\times 3.14\times 10.5\times 60°}{ 360°}\right)$$

$$= 21 + \left(\frac{3956.4}{ 360°}\right)$$
 

$$= 21 + 11$$ 

$$= 32 cm$$ 

Hence the perimeter of the sector is 32 cm