[填空题]
A person exerts a forinx jq s74ec-n4qpkk4dj2q(9 ce of 55 N on the e65beo kh.v:ht5 tg(nlnd of a door 74 cm wide. What is the magnitude of the gnblkt56 5v:eoh .(th 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? $m \cdot N$