We have,
A cylinder height = 10 cm and radius is 6 cm.
Volume of a solid cylinder
=πr2h =π×62×10 =360π Flat surface area of cylinder
=2πr2=2π×62=72πcm2 A solid cylinder is melted into two cones with same height
10cm.
The ratio of volume of two cone is 1: 2 .
Means if we divide
360π into 1: 2 then
120π:240π So one cone volume is
120π and second has
240π.
∴ Cone volume
=r2h Then first bigger cone has
R radius. then
240π=R2h⇒R2=72 Then flat surface area of first cone
=πR2=72π Then second smaller cone has
r radius. then
120π=r2h⇒r2=36 Then flat surface area of second cone
=πr2=36π Total surface area of cone
=72π+36π=108π So flat surface area from cylinder to cone is increased by
36π which is 50
% increase.