[填空题]
A person exerts a force of 55 N on yjdm5 +e 2)sx- tnr6gdthe m45swer/elwtn )pj3/end of a door 74 cm wide. What is the magniee/ 3/s4tpw5ln m)wrj tude of the 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? $m \cdot N$