If 3 vectors can be rearranged in a triangle in which only the head and tails of the vectors make contact, i.e. there is no head to head or tail to tail contact, then equilibrium seems to be the case, meaning that the object is not moving (the triangle of forces rule).
Force C, D and E can be rearranged in such a way, see hereunder. However, there are two more forces (A AND B) of which one seems to be disrupting equilibrium. My question is: “What is a proper method to conceptually define which force, A or B, is disrupting equilibrium, when you have used the Triangle of Forces rule for force C, D and E? Please, take into account that I am neither allowed to use paper, nor use a calculator to answer this question.
Sources for theory are also welcome. Thanks in advance for your assistance.