[填空题]
A person exerts a force of 55 N on the end of a door 74 c0lpr9 ,qwxw)y t48pppm wide. What is the magy ,x9qwp0 )twp4pr8lp:soqy fqk(;ipd je-9ngl)0x *nitude of the torque if the*j; qsn9d-)lgipfy0q oe(x: k force is exerted (a) perpendicular to the door $m \cdot N$ (b) at a 45 $^{\circ} $ angle to the face of the door? $m \cdot N$