$??解：相似，理由如下：??$
$??由圖可知，A_{1}B_{1}=\sqrt{22+22}= 2\sqrt{2}，??$
$??A_{2}B_{2}=\sqrt{12+12}=\sqrt{2}，??$
$?? A_{1}C_{1}=4， A_{2}C_{2}= 2，??$
$??B_{1}C_{1}=\sqrt{22+62}=2\sqrt{10}??$
$??B_{2}C_{2}=\sqrt{12+32}=\sqrt{10}??$
$??因?yàn)閈frac {A_{1}B_{1}}{A_{2}B_{2}}=\frac {A_{1}C_{1}}{A_{2}C_{2}}=\frac {B_{1}C_{1}}{B_{2}C_{2}}??$
??$所以△A_{1}B_{1}C_{1}∽△A_{2}B_{2}C_{2}$?
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