[tex]Perimetrul =12+9+6=27\\Aria= \sqrt{p(p-a)(p-b)(p-c)} , unde \\ p=\frac{a+b+c}{2} =\frac{27}{2} \\ Aria= \sqrt{\frac{27}{2}*(\frac{27}{2} -12)*(\frac{27}{2} -9)*(\frac{27}{2}-6) } =\\ =\sqrt{\frac{27}{2}*\frac{3}{2} *\frac{9}{2} *\frac{15}{2} } =\\=\sqrt{\frac{10935}{16} } =\frac{\sqrt{10935} }{4}[/tex]