Find the angle between two forces of equal magnitude when the magnitude of their resultant is also equal to the magnitude of either of these forces:

Explanation

When two forces of equal magnitude act at an angle, the magnitude of their resultant can be found using the parallelogram law of vector addition. For the resultant to be equal to the magnitude of either of the forces, they must be arranged such that the angle between them is 120˚. This is a result of the law of cosines applied to the situation where the resultant magnitude equals one of the forces: R = 2Fcos(θ/2). When θ = 120˚, cos(60˚) = 0.5, thus satisfying the condition.The incorrect options suggest angles where the resultant magnitude would not match the individual forces' magnitude due to their trigonometric relationships.