I worked this problem through using Fnet = ma. Becuase there is no acceleration and the forces all cancel each other out because there is no displacement, i set Fnet=0. Using forces a and b, i got 0=220+117+b. solved for b and got -337. this was not the right answer. i feel like i have to factor in the angel. but then i feel like i should have an angel for c...which is not given.
In a two-dimensional tug-of-war, Alex, Betty, and Charles pull horizontally on an automobile tire at the angles shown in the picture. The tire remains stationary in spite of the three pulls. Alex pulls with force FA of magnitude 220 N, and Charles pulls with force FC of magnitude 177 N. Note that the direction of FC is not given. What is the minimum magnitude of Betty's force FB ? (Angel of 149 degrees)