Three equal masses of each m kg are fixed at the vertices of an equilateral triangle ABC.

a)What is the force acting on a mass 2m placed at the centroid G of the triangle.

b)What is the force if the mass at the vertex Ais doubled?

[AG=BG=CG=1m]

textbook page no. 187 example: 8.2please explain to me properly i am not able to understand that.