[tex]a=|AB|=\sqrt{(10+11)^2+(-4+4)^2}=\sqrt{21^2+0^2}=21\\D=(5,-4)\\h=|CD|=\sqrt{(5-5)^2+(-4-8)^2}=\sqrt{0^2+12^2}=12\\b=|AC|=\sqrt{(5+11)^2+(8+4)^2}=\sqrt{16^2+12^2}=\sqrt{256+144}=\sqrt{400}=20\\c=|BC|=\sqrt{(5-10)^2+(8+4)^2}=\sqrt{(-5)^2+12^2}=\sqrt{25+144}=\sqrt{169}=13\\P=\frac{a*h}{2}=\frac{21*12}{2}=21*6=126\\Obw=a+b+c=21+20+13=54[/tex]
