[填空题]
A person exerts a fornq 6.yjj: jdy8ce of 55 N on the esz p::5 vj:wudbncj8bc 6 )ay4nd of a door 74 cm wide. What is the magnitude of the torque if:d6ybu: n ccbzpj 8w)a: js4v5 the force is exerted (a) perpendicular to the door $m \cdot N$ (b) at a 45 $^{\circ} $ angle to the face of the door? $m \cdot N$