三角形ABC相似于三角形DAC
AD:AC=AB:BC
因为AB=AC=BD
BC=BD+DC=AC+AD
所以AD:AC=AC:(AC+AD)
得5AC²/4=(AC/2+AD)²
√5AC/2=AC/2+AD
所以AD=（√5-1）AC/2
AD:AC=（√5-1）/2
已知:三角形ABC中,AB=AC,角B=36°,点D在BC上,且AD=DC,则AD:AC=
已知:三角形ABC中,AB=AC,角B=36°,点D在BC上,且AD=DC,则AD:AC=
数学人气：641 ℃时间：2020-01-29 07:13:12
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