[填空题]
A person exerts a force o ha in+te8k41mf 55 N on the end of a door 74 cm wide. What is th8m/)sm(w v mr kn-l*w;;0 ia0xho4 gdc*mghqde magnitude of the torque i8gmrn)lds mxh4q0wm* kcg h/-wm0*ivo ;;a (df the force is exerted
(a) perpendicular to the door $m \cdot N$
(b) at a 45 $^{\circ} $ angle to the face of the door? $m \cdot N$