解:F=ma=m -RA0.RO 2TR ∑F3=0,∑ Fr cos 8-F=0 ∑F=0,∑F Hli Sin.=0 令6.→0. =[%心取DCSO=m b2丌 27 B 2Ro2 Sin de=如Ro2 2丌解: 2 2    R R R m F m a i n Ii = i i =  = 0,  cos − = 0 Fx FIi  FA Fy = 0, FIi sin  − FB = 0 令 → 0,  i        2 mR R 2 m F 2 2 2 0 A = =  cos d        2 mR R 2 m F 2 2 2 0 B = =  sin d