圖示桁架結構桿①的軸力大小為:()
A.-2P B.-P C.-P/2 D.P
A.-P/2 B.P C.3/2P D.2P
圖示桁架結構桿①的軸力為:()
A.3P/4 B.P/2 C.0.707P D.1.414P