[tex]3.\\ \\ \it \sqrt{(3-\sqrt{10})^2}+\sqrt2(2\sqrt2-\sqrt5)=|3-\sqrt{10}|+2\cdot2-\sqrt{10}=\\ \\ =-3+\sqrt{10}+4-\sqrt{10}=1[/tex]
[tex]4.\\ \\ \it MN=\dfrac{BC}{2}=\dfrac{12}{2}=6\ cm;\ AN=\dfrac{AB}{2}=\dfrac{6}{2}=3\ cm;\ AM=\dfrac{8}{2}=4\ cm\\ \\ \\ \mathcal{P}_{AMN} = AN+AM+NM=3+4+6=13\ cm[/tex]
