求线组:Fb=mgq bx = mgp xb2=912=9 F b L xb= Fxbl+ Fxb2 F b2÷a/ g4(F+F)2 L g L F xb2 F b1 L+oh L+ohg mg 106个Q 介长10/16 ( ) g xb g g xb xb xb g xb xb xb xb xb g xb z g xb L h mgL F L h h F L F F h L mgL F F F F L F h L mgL L h L mg F F r F mg           + − + =         + = − = +         = = − = − = 1 2 1 1 1 2 2 1 2 1 2 2 1 ( ) 求 线组： Fxb2 Fxb1 ( ,0) 1 g h mgL Fbx = mg