posted by Bill .
An equilateral triangle 100.0 m on a side has a m1 = 15.00 kg mass at one corner, a m2 = 75.00 kg mass at another corner, and a m3 = 120.00 kg mass at the third corner. Find the magnitude and direction of the net force acting on the 15.00 kg mass.
Vectorially add the forces due to m2 and m3, acting upon m1. Use Newton's universal law of gravity for the individual forces.