AB=√(xB-xA)²+(yB-yA)²
AB=√(4-2)²+(0-2)²
AB=√2²+(-2)²
AB=√4+4
AB=√8
AB=2√2
AC=√(xC-xA)²+(yC-yA)²
AC=√(2-2)²+(-2-2)²
AC=√0²+(-4)²
AC=√16
AC=4
BC=√(xC-xB)²+(yC-yB)²
BC=√(2-4)²+(-2-0)²
BC=√(-2)²+(-2)²
BC=√4+4
BC=√8
BC=2√2
PΔABC=AB+BC+AC
PΔABC=2√2+2√2+4
PΔABC=4√2+4