Find the magnitude of the resultant force and the angle between the resultant and each force:

Forces of 2 lbs and 12 lbs at an angle of 60 degrees to each other.

2 answers

if we let
u = 12.0i
v = 2cos60° + 2sin60° = 1.0i + 1.732j

u+v = 13.0i + 1.732j
in polar form, that is (13.115,7.6°)
or, if you're not into vectors, try using the law of cosines and law of sines:

the resultant r is

r^2 = 2^2 + 12^2 - 2*2*12 cos120°
r^2 = 172
r = 13.115

the angle θ between the big force and the resultant is

sinθ/2 = sin120°/13.115
sinθ = 0.1321
θ = 7.6°