图示桁架结构杆①的轴力为:()
A.-P/2 B.P C.3/2P D.2P
A.3P/4 B.P/2 C.0.707P D.1.414P
图示结构A支座反力偶的力偶矩MA为:()
A.0 B.1kN·m,右侧受拉 C.2kN·m,右侧受拉 D.1kN·m,左侧受拉