Cho tam giác ABC. Đường cao AH. $p,p_{1},p_{2}$ là chu vi các tam giác ABC, ABH, ACH. CMR: $\widehat{A}=90^{o}\Leftrightarrow p^{2}=p_{1}^{2}+p_{2}^{2}$
CMR: $\widehat{A}=90^{o}\Leftrightarrow p^{2}=p_{1}^{2}+p_{2}^{2}$
Started By chatditvit, 27-06-2015 - 22:38
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