cuongmen78

giai cau 5b.ta co:\[\begin{array}{l}
{\left( {\frac{{AI}}{{AM}} + \frac{{BI}}{{BN}} + \frac{{CI}}{{CP}}} \right)^2} \ge 3\left( {\frac{{AI.BI}}{{AM.BN}} + \frac{{BI.CI}}{{BN.CP}} + \frac{{CI.AI}}{{AM.CP}}} \right) \\
\Leftrightarrow 4 \ge 3\left( {\frac{{{{\left( {R - OI} \right)}^2}}}{{AM.AN}} + \frac{{{{\left( {R - OI} \right)}^2}}}{{BN.CP}} + \frac{{{{\left( {R - OI} \right)}^2}}}{{AM.CP}}} \right) \\
\Rightarrow dpcm \\
\end{array}\]