How to Find the Components of the Inertia Tensor Matrix for Point Masses?

lulamuz27
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Homework Statement


Hi everyone, I need some help to know how to find the components of the inertia tensor matrix of a rigid body formed by a gruop of point masses attached to bars with no mass.
I have 3 masses with cartesian coordenates: 1 (a,a,0), 2 (a,0,0) and 3 (-a,-a-0).





The Attempt at a Solution


The book says: Ixx= 2ma^2, Ixy= -2ma^2, why??


Thank you!
 
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Do you know the general formulas for the elements of the inertia tensor? That would be a good place to start.
 
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