Answer
The perpendicular distance from the direction of each force to the axis of rotation must be the same. Since the magnitude of the forces are the same, these two forces create equal and opposite torques. Therefore, the sum of the torques is zero.
Work Step by Step
Although the forces may be applied at different points which may be different distances from the axis of rotation, the two forces act in opposite directions along the same straight line. Therefore, the perpendicular distance from the direction of each force to the axis of rotation must be the same. Since the magnitude of the forces are the same, these two forces create equal and opposite torques. Therefore, the sum of the torques is zero.
