证明：∵AB=BB1∴平面ABB1A1和平面CBB1C都是正方形∵AC1⊥平面A1BD,∴AC1⊥A1D,∴△A1AD和△ACC1相似∴A1A/AD=AC/CC1∵A1A=CC1,AD=AC/2∴AC=根号2×AA1∴△ABC为等腰直角三角形,∴△A1B1C1也是∴C1B1⊥A1B1∵C1B1⊥B...
证明：∵AB=BB1∴平面ABB1A1和平面CBB1C都是正方形∵AC1⊥平面A1BD,∴AC1⊥A1D,∴△A1AD和△ACC1相似∴A1A/AD=AC/CC1∵A1A=CC1,AD=AC/2∴AC=根号2×AA1∴△ABC为等腰直角三角形,∴△A1B1C1也是∴C1B1⊥A1B1∵C1B1⊥B...