[填空题]
A person exerts a force of 55 N on the 375y)w6 os7 fvo)wxo8, tq ngpnz)xiwend of a a qo8s 4yb*.acktpll*3c56agdoor 74 cm wide. What is the magnitude of the torque if the forcegbpcat s yackq*8a .*lo3l64 5 is exerted (a) perpendicular to the door $m \cdot N$ (b) at a 45 $^{\circ} $ angle to the face of the door? $m \cdot N$