取杆AB为z轴 E D D 画受力图 F B D=lDI S TC i G S=Sk W=-10sin30°c045i-10sin30°c0s45-10cos30°k 1515 取杆AB为z 轴 画受力图. G W A B C E D F  x S z TC TD y TD = TD i TC = TC j S = S k W = -10sin30o cos45o i -10sin30o cos45o j -10cos30o k