Consider an area with asymmetrical mass distribution. The moments of inertia about arbitrary coordinate axes are obtained by integrating the moment of inertia for an infinitesimal area element. Consider another coordinate system inclined at an angle to the initial coordinate system. Again, the moments and the product of inertia along the inclined axes can be expressed in terms of the inclined coordinates and the area element. Using the transformation relations for both coordinates, the moments of inertia reduce to a function of the initial coordinates. The terms are further expanded, and trigonometric identities are used to obtain the moment of inertia about the inclined axes. Similarly, using the transformation relations in the expression for product of inertia gives the product of inertia about the inclined axes. Adding the moment of inertia about the x and y axes, gives the polar moment of inertia along the z-axis that is independent of the orientation of the inclined axes. The moment of inertia about inclined axis is used to determine plate stiffness when subjected to shear forces.