V
vuotlensophan


cho tam giac ABC. I la tam đuong tron noi tiep tam giac.
cm: AB.AC+BC.BA + CA.CB \geq [TEX]{(IA+ IB+IC)}^{2}[/TEX]
cm: AB.AC+BC.BA + CA.CB \geq [TEX]{(IA+ IB+IC)}^{2}[/TEX]
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