[填空题]
A person exerts a force of 0iw:z2af1d wg55 N oplq (p pt2p 4s7qaq9j-n the end of a door 74 cm wide. What is the magnitude of the torque if the force is-qlp 7s4ppj p9( qt2qa exerted (a) perpendicular to the door $m \cdot N$ (b) at a 45 $^{\circ} $ angle to the face of the door? $m \cdot N$