[填空题]
A person exerts a force of 55 N o q ceian4h9cr8ml :7*en the end of a door 74 cm 0 kzh/nh l+tt )+n4pqsd0ss.dwide. What is the magnitude of the toqkdsls)n+/+s p 0t.0 n4thhd zrque 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? $m \cdot N$