We can also say,
Maximum value of product of inertia = (Difference of two principal second moments of area)/2.
Polar Moment of area
We know that,
where r is the radial coordinate of a point. Note that r is independent of the inclination of the coordinate system, the sum Ixx + Iyy is independent of the inclination of the reference. This sum is also called as the polar moments of area Ip.
