Question

find the area of a circular ring whose external and internal radii are 21 cm and 14 cm respectavly

Answer 1

Hii !!


External radius ( R ) = 21 cm


And,

Internal radius ( r) = 14 cm.


Therefore,

Area of ring = π ( R² - r² )



=> π { 21² - 14² }



=> π ( 441 - 196 )


=> 22/7 × 245



=> 22 × 35


=> 735 cm².



Hence,


Area of ring = 735 cm².