(1).设BD=X,CB^2=4+X^2,AC^=4=4X^2,AB^=9X^2
AB^2=AC^2+BC^2
4+X^2+4+4X^2=9X^2
X=根号2
所以:AB=3倍根号2
(2).设BD=X,E为AB中点
CE^=4+1/4X^2=9/4X^2
X=2/5根号10
AB=6/5根号10
(1).设BD=X,CB^2=4+X^2,AC^=4=4X^2,AB^=9X^2
AB^2=AC^2+BC^2
4+X^2+4+4X^2=9X^2
X=根号2
所以:AB=3倍根号2
(2).设BD=X,E为AB中点
CE^=4+1/4X^2=9/4X^2
X=2/5根号10
AB=6/5根号10