Hi all,
Right, I cant seem to get this one correct, the question is:
Two forces, each of magnitude 5N, act at the point P, as shown in the diagram. Their resultant also has magnitude 5N. By drawing a vector triangle to represent the two forces and their resultant, find the angle between the two forces.
heres a rough description of the diagram, one 5N force is on the bearing 090, along the x axis basically, and the other is (after looking the answer i now know this) on the bearing 330. i need to find the angle between these two forces. (the smaller angle)
using a^2=b^2+c^2-2bcCosA you get cosA=1/2 which gets you 60 degrees. but the answer is 120 degrees, so i somehow need to get cosA=-1/2... but how? does the one vector on the bearing 330, so essentially in the other direction, make it a -5 quanitity when put into the formula for the angle or?
i know that seems very confusing, any help would be great!