a) Find the moment of inertia of a sphere about a tangent to the sphere, given the moment of inertia of the sphere about any of its diameters to be `(2MR^2)/5`, where M is the mass of the sphere and R is the radius of the sphere.
b) Given the moment of inertia of a disc of mass M and radius R about any of its diameters to be `MR^2/4`, find its moment of inertia about an axis normal to the disc and passing through a point on its edge.