Question Checkup 30.3.1: The torque given by Eq. (30.17) has a maximum magnitude at θ......

For \theta = 90°, the direction of the cross product of \mu and B is out of the page; a torque out of the page implies that the loop will turn counterclockwise (right-hand rule). Similarly, for \theta = -90°, \tau is into the page; such a torque implies that the loop will turn clockwise.