First we will find moment of inertia about an axis passing through its center and       perpendicular to the plane i.e. Icom                           For this, consider an elementary ring of mass dm and width dr at a distance r from the center of       disc. Then, moment of inertia for the elementary ring is- dI=dm.r2                    As, dm=MR2.2πrdr     Then, Icom =dIring=0RMR2.2πrdr.r2=MR2/2    Now, to find moment of inertia about axis through its tangent, we use parallel axis theorem-    I=Icom+ MR2,  as h=R here. I=3MR22