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BT1
CMR
[TEX]\frac{1}{p-a}+\frac{1}{p-b}+\frac{1}{p-c}\geq2(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}[/TEX]
BT2Cho tam giác ABC. CMR
[TEX]\frac{3S}{R}\leq a.cos^2.\frac{A}{2}+b.cos^2.\frac{B}{2}+c.cos^2.\frac{C}{2} \leq \frac{3S}{2r}[/TEX]
CMR
[TEX]\frac{1}{p-a}+\frac{1}{p-b}+\frac{1}{p-c}\geq2(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}[/TEX]
BT2Cho tam giác ABC. CMR
[TEX]\frac{3S}{R}\leq a.cos^2.\frac{A}{2}+b.cos^2.\frac{B}{2}+c.cos^2.\frac{C}{2} \leq \frac{3S}{2r}[/TEX]
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