(N/A) $1$. Theorem of Perpendicular Axes: This theorem states that the moment of inertia of a planar lamina about an axis perpendicular to its plane $(I_z)$ is equal to the sum of its moments of inertia about two mutually perpendicular axes lying in its plane ($I_x$ and $I_y$) and intersecting at the point where the perpendicular axis passes through the body. Mathematically,$I_z = I_x + I_y$.
$2$. Theorem of Parallel Axes: This theorem states that the moment of inertia of a rigid body about any axis $(I)$ is equal to the sum of its moment of inertia about a parallel axis passing through its center of mass $(I_{cm})$ and the product of the mass of the body $(M)$ and the square of the perpendicular distance $(d)$ between the two axes. Mathematically,$I = I_{cm} + Md^2$.