The height of a cone is 21cm. Find the area of the base if the slant height is 28cm.

Explanation

given,

`h=21cm`

`l=28cm`

so `r=(l^2-h^2)^(1/2)`

`r=(28^2-21^2)^(1/2)`

`r=7(7)^(1/2)cm`

so area of base `=(22/7)xx[7(7)^(1/2)]^2`

`=1078cm^2`