Find the total surface area of a cone, if its slant height is 21 m and diameter of its base is 24 m.
We have,
Slant height of cone(l ) = 21 m
Radius of cone ( r )= 12 m
Total surface area = πr2+ πrl= πr(r+l)
= 
×12(12+21) m2
=
×12×33 cm2=1244.57 m2
7