In the formula \( W = Fd \cos \theta \), where:
- \( W \) is the work done,
- \( F \) is the magnitude of the force,
- \( d \) is the magnitude of the displacement,
- \( \theta \) is the angle between the direction of the force \( F \) and the direction of the displacement \( d \).
Thus, \( \theta \) represents the angular relationship between the applied force and the direction of motion (displacement). When \( \theta = 0^\circ \), the force is in the same direction as the displacement, and the work done is maximized. When \( \theta = 90^\circ \), the force is perpendicular to the displacement, and no work is done.