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如图,在直三棱柱A1B1C1-ABC中,C1C=CB=CA=2,AC⊥CB,D、... 已知正三棱柱abc-a1b1c1延长cb到d,bd=cb
已知正三棱柱ABC-A1B1C1中,延长CB至D,使BD=CB,求证面AB1D⊥面A1AC1C 证明:正三棱柱AB=BC,∠ABC=∠BAC=60°A1A⊥面ABCAD∈面ABCA1A⊥ADBC=BDAB=BDBAD=∠BDA=?∠ABC=...
已知正三棱柱ABC-A1B1C1中,延长CB至D,使BD=CB,求证面AB1D⊥面A1AC1C 证明:正三棱柱AB=BC,∠ABC=∠BAC=60°A1A⊥面ABCAD∈面ABCA1A⊥ADBC=BDAB=BDBAD=∠BDA=?∠ABC=...