[填空题]
A flat circle of rada1ez5u 9y/p4q odj*z9 q aml;jj s(a-nius 18 cm is placed in a uniform elex* 8dumd6lg 7lsa ,1)ikhy.hzctric field of magnitudes,*ly)i .g hu8 17d6mkzldx ha $ 5.8\times10^{2 }\,N/C$ What is the electric flux through the circle when its face is
(a) perpendicular to the field lines, $N\cdot m^2/C$
(b) at 45° to the field lines, $N\cdot m^2/C$
(c) parallel to the field lines?
