Hello,

The moment of inertia of a uniform disc and a hollow right circular cone is calculated using the same formula.

M.I=mr^2/2

This is due to the fact that when a hollow right circular cone is sliced along its slanting side and the material is stretched out, the cone's surface becomes a circle. This form is similar to that of a disc, which is a circular as well. As a result, they both possess the same MI formula.

Hope you got it

Good luck!!