Question

find the slant height of the cone whose radius is 9 cm and height is 12 cm.

Answer 1

given radius= 9 cm
         height =12 cm
slant height=√r²+h²
                 =√9²+12²
                 =√81+144
                 =√225
                 ⇒15 cm 
slant height =15cm

Answer 2

by pythagoras theorem,
l^2=r^2+h^2
here,l^2=12^2+9^2=225
so l,i.e.slant height equals=root of 225=15cm