Theorem of parallel axis

It states that if the M.I. of plane area about the axis passing through the C.G. can be denoted by I_G. The M.I. of area about any other axis AB, parallel to 1^st and a distance 'h' from C.G. can be given by

I_AB = I_G  + a.h²

Where;

I_AB  = M.I. of area about an axis AB _IG  = M.I. of area about its C.G.

a = Area of section

h = Distance between C.G. of section and axis AB

This formula gets reduced to;

I_XX  = IG  + a.h²; h = distance from x - axis i.e.; Y - y

I_YY  = IG  + a.h²; h = distance from y - axis i.e.; X - x