Dynamics 17-11| The assembly is made of the slender rods

Question: The assembly is made of the slender rods that have a mass per unit length of 3 kg/m. Determine the mass moment of inertia of the assembly about an axis perpendicular to the page and passing through point O.
Problem 17-11 from:
Engineering Mechanics: Dynamics, 14th edition
Russell C. Hibbeler
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Could you do kinetics of rigid bodies? A very complex topic