根据几何关系,有 O C‖c x=isin a A o B S x=lcosas a AlcoA S yA=-lsin as a n18 l mi g Isin a lcosas a isin as a yB-IcoSa 2/sin as a yc=2Icosa Fu 8x+FB. XB+m,8. 5 yA+mg 0yB+m28-0yc=0 2m, /sin a@ lcosao a-2mglsin as a-2m, glsin as a=0 (m1+m2)g m,icosa C l l l l   O1 x y A B m1 g m1 g m2 g  rB rA rC 根据几何关系，有      2 cos cos sin cos sin y l y l x l y l x l C B B A A ＝ ＝ ＝ ＝ ＝ −           δ 2 sin δ δ sin δ δ cos δ δ sin δ δ cos δ y l y l x l y l x l C B B A A − − − − ＝ ＝ ＝ ＝ ＝ FIB FIA 2 sin cos δ 2 1 sin δ 2 2 sin δ 0 2 m1 l   l   − m gl   − m gl   =   cos ( ) 1 2 1 2 m l m + m g = δ δ δ δ δ 0 FIA  xA + FIB  xB + m1 g  yA + m1 g  yB + m2 g  yC =