Two identical masses of 5kg each are placed at the vertices A and B of an equilateral triangle ABC with side length 2m.
Force due to A on C: FAC = GmAmCr2 = 6.67×10−115×1022 = 8.34×10−10N. Force due to B on C: FBC = 8.34×10−10N (equal magnitude, 60° apart). Resultant: FR = FAC2+FBC2+2FACFBCcos60∘. FR = (8.34×10−10)2+(8.34×10−10)2+2(8.34×10−10)2(0.5). FR = 8.34×10−101+1+1 = 1.44×10−9N.
Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.