[填空题]
A person exerts a force oq/otn-wkben4zx0h e6k8 v;l. f 55 N on the end 705u f.apqhwo of a door 74 cm wide. What is the magnitude of theu0w.7a opf qh5 torque if the force is exerted (a) perpendicular to the door $m \cdot N$ (b) at a 45 $^{\circ} $ angle to the face of the door? $m \cdot N$