I would appreciate any help on this problem: In Fig. 14-18a, a square of edge length .232m is formed by four spheres of masses m1 = .00372 kg, m2 = .00958 kg, m3 = .00408 kg, and m4 = .00835 kg. In unit-vector notation, what is the net gravitational force from them on a central sphere with mass m5 = .00424 kg? I started out by using F = G*Ma*Mb/r^2. So for the x-direction, it would be something like: Fi = G*M3*M4/r^2 + G*M1*M2/r^2, and similar things for the y-direction. But I don't know how to include the m5 into my equations. Do I have to involve angles and trig functions?