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# the derivatio of the formula of frustum of cone

Asked by Vivek Bhakat(ATOMIC ENERGY CENTRAL SCHOOL NO 1) , on 9/12/10

Hi!

soorampalli_keerthana...  correctly gives the derivation for the formula of curved surface area and total surface area of frustum of cone.
Good answer!! We really appreciate your contribution to this forum. Keep posting!

Note: Volume of frustum of the cone can be calculated by subtracting the volume of the smaller cone from the volume of the bigger cone.

Best wishes!

Posted by gopal.mohanty...on 10/12/10

This conversation is already closed by Expert

Let ABC be a cone. A frustum DECB is cut by a plane parallel to its base. Let r 1 and r 2 be the radii of the ends of the frustum of the cone and h be the height of the frustum of the cone.

In ΔABG and ΔADF, DF||BG

∴ ΔABG ∼ ΔADF

CSA of frustum DECB = CSA of cone ABC − CSA cone ADE

CSA of frustum =

Posted by soorampalli_keerthana...on 9/12/10