[tex] A(2,4); B(4,2); C(2,0) \\ \\ AB= \sqrt{(x_{2}- x_{1})^{2}+ (y_{2}- y_{1})^{2}}; AB= \sqrt{(4- 2)^{2}+ (2-2)^{2}}= \sqrt{4} =2 \\ \\ AC= \sqrt{(x_{3}- x_{1})^{2}+ (y_{3}- y_{1})^{2}}; AC= \sqrt{(2- 2)^{2}+ (0-4)^{2}}= \sqrt{16} =4[/tex]
[tex]BC= \sqrt{(x_{3}- x_{2})^{2}+ (y_{3}- y_{2})^{2}};BC= \sqrt{(2-4)^{2}+(0-2)^{2}}= 2 \sqrt{2}[/tex]
Perimetrul=AB+AC+BC =2+4+2√2=6+2√2=2(3+√2) cm
