Two forces of equal magnitude act on an object so that the angle between their directions is 60 degrees. If their resultant has a magnitude of 20 N, find the magnitude of the equal forces.
2 * m / cos(60º / 2) = 20 N
they have magnitude x, where we find x using the law of cosines
20^2 = x^2 + x^2 - 2x^2 cos120°