We have 3 known forces acting, we should be able to
analytically predict a fourth force to add so that the system is
in equilibrium (Fnet = 0).
A Force 1: 10 N
Direction 1: 60%
B Force 2: 10 N
Direction 2: 125°
C Force 3: 10 N
Direction 3: 290°
Now, use component algebra to calculate a forth vector, D,
that when added to the system will result in equilibrium.
