设三棱椎ABCD,AB=x,则表面积=S△ABC+S△ABD+S△ACD+S△BCD=(1/2)AC*BC*sin∠ACB+(1/2)AD*BD*sin∠ADB+(1/2)AC*AD*sin60°+(1/2)BC*BD*sin60°=(1/2)(sin∠ACB+sin∠ADB+2sin60°)当∠ACB=90°且∠ADB=90°时,表面积...