[填空题]
A person exerts a force of 55 4 6jgb qlnud8:g(aw t:N on the end of a door 74 cm wide. What is thot uf86bqc77 ee magnitude of 7obec t7q6u f8the 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? $m \cdot N$