Question

Find the surface area of a sphere of diameter 21 cm

`["Assume "pi=22/7]`

 

Answer 1

`"Radius (r) of sphere "= "Diameter"/2 =(21/2)cm=10.5cm`

Surface area of sphere = 4πr²

`=[4xx22/7xx(10.5)^2]cm^2`

= 1386 cm²

Therefore, the surface area of a sphere having diameter 21 cm is 1386 cm².