The question is: The 150lb. force shown is the resultant of two forces, one of which is shown. Determine the other force. I cannot figure out how to get the other force. I tried using the parallelogram method and method of components, but have been way off on the answers. The answers on the back of the book says the other Force=87.9lb and θ=3.87°. I tried doing the x and y components of each answer but i just end up back with the same numbers i started out with. I have tried the pythagoream theorm by subtracting 150 squared from 75 squared which gave me an answer of 130 when rounded, from there I got lost. I'm just wondering how to actually determine the other force the correct way. I've been reading the book examples and they only tell you just how to determine the resultant, but not the force, if only one is given.