Question

The upper part of a cone has removed by cutting it by a plane parallel to the base.The covered surface of the remaining part is 8/9 of the total covered surface. At what hight above the base the cone has been cut-off ?

Answer 1

if we take total height of the cone =H
then the height of frustum should be=H/2
if height of frustum will be H/2 then the remaning part c.s.a of frustum will be 8/9 of c.s.a of cone.
 

Answer 2

Answer:

if we take total height of the cone =H

then the height of frustum should be=H/2

if height of frustum will be H/2 then the remaning part c.s.a of frustum will be 8/9 of c.s.a of cone.