(2)合力F的大小和方向与主矢F相同。x 值可根据合力矩定理求得 F=232.9kN F=-670.1kN M=∑M(F)=-2355N·m M O A O A 7.840 7.840 M=M(FR)=M(R)+Mo()=M(FRv=F M./F Fn=3.514m RO A C 70.84o Mo ' FR ' FRx ' FRy O A C 70.84o FR FRx FRy x (2) 合力FR的大小和方向与主矢FR /相同。x 值可根据合力矩定理求得： M M ( ) M ( ) M ( ) M ( ) F x o o R o Rx o Ry o Ry Ry = F = F + F = F = • x = Mo FRy = 3.514m F F . k N F F . k N y ' Ry x ' Rx 670 1 232 9 = = − = =   Mo = Mo (F) = −2355 k N • m