如图,∠ACB=∠ADC=90°,BC=a,AC=b,AB=c,要使△ABC∽△CAD,只要CD等于(  ) A.b2c B.b2a C.abc D.a2c

问题描述:

如图,∠ACB=∠ADC=90°,BC=a,AC=b,AB=c,要使△ABC∽△CAD,只要CD等于(  )
A.

b2
c

B.
b2
a

C.
ab
c

D.
a2
c

假设△ABC∽△CAD,

CD
AC
AC
AB

即CD=
AC2
AB
=
b2
c

∴要使△ABC∽△CAD,只要CD等于
b2
c

故选A.