What is the difference between the area moment of inertia of a triangular section about its base and the area moment of inertia about its centroidal axis parallel to the base (where b is the base and h is the height)?

Determine the mass moment of inertia of three identical uniform rods (each of mass m and length l) arranged to form an equilateral triangle, about an axis perpendicular to the plane of the triangle and passing through its centroid.

Determine the mass moment of inertia of three identical rods (each of mass m and length l) arranged to form an equilateral triangle, about an axis perpendicular to the plane of the triangle and passing through its centroid.