[填空题]
A person exerts a forct7pn t:ux 69q3we4gaye of 55 N on the end of a door h01 b5joj(5xcyuuje- 74 cm wide. What is the magnitude of the jxehu5y1cjb j0o (5- utorque 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? $m \cdot N$