2兀d+ COSO lo12( F uoi/2R r2T cos 6d6 ld 2-r ⊙By Lo//2R 2n sIn Ade do d+roseo d d F. d F 2 dF ‖2d7 R F=Fi=1012(1 )i 3 2 Ri d R d F F i I I x    (1 ) 2 2 0 1 2 − = =  − (1 ) 2 2 0 1 2 d R d I I − =  −  + = 2π 0 0 1 2 cos cos d 2π     d R I I R Fx 0 cos sin d 2π 2π 0 0 1 2 = + =      d R I I R Fy x y F  Fy d  d Fx  d O 2 I 1 I d  I l  2 d R d . B 