PTHĐGĐ là:
|x|=2
=>x=2 hoặc x=-2
=>A(2;2); B(-2;2)
\(OA=\sqrt{\left(2-0\right)^2+\left(2-0\right)^2}=2\sqrt{2}\)
\(OB=\sqrt{\left(-2-0\right)^2+\left(2-0\right)^2}=2\sqrt{2}\)
\(AB=\sqrt{\left(-2-2\right)^2+\left(2-2\right)^2}=4\)
\(C=2\sqrt{2}+2\sqrt{2}+4=4\sqrt{2}+4\left(cm\right)\)