quick answer please 
Three objects each of mass 'm' are placed at the corners of an equilateral triangle of side 'l' . What is the gravitational force acting on each mass due to other masses is 
$$\begin{gathered} \text{1) }\frac{{\text{Gm}}^2}{\sqrt{3{\text{l}}^2}} \\ \text{2) }\frac{\sqrt{3}{\text{Gm}}^2}{2{\text{l}}^2} \\ \text{3) }\frac{\sqrt{3}{\text{Gm}}^2}{{\text{l}}^2} \\ \text{4) }\frac{{\text{Gm}}^2}{{\text{l}}^2} \end{gathered}$$