[tex] \it 10)\\ \\ a= |\sqrt2-\sqrt3| = \sqrt3-\sqrt2
\\ \\
b= |\sqrt3+\sqrt2| = \sqrt3+\sqrt2
\\ \\
ab=(\sqrt3-\sqrt2)(\sqrt3+\sqrt2) =(\sqrt3)^2 -(\sqrt2)^2 =3-2=1
\\ \\
----------------------- \\ \\
11)\ \ R = 8:2 = 4\ cm [/tex]
[tex] \it 12)\ \ \mathcal{A} = \dfrac{AB\cdot AC\cdot sinA}{2} =\dfrac{6\cdot10\cdot sin30^o}{2} = 3\cdot10\cdot\dfrac{1}{2} = 3\cdot5=15\ cm^2 [/tex]
