Answer:
Step-by-step explanation:
Perimeter = 16 km
s = 8 km
Area = [tex]\sqrt{s(s-a)(s-b)(s-c)}[/tex]
Area = 12 sq km
Let the third coordinate be (x,y).
Then, a = [tex]\sqrt{(2-2)^{2}+(2-(-1))^{2} }[/tex]
=3
b = [tex]\sqrt{(x-2)^{2}+(y-2)^{2} }[/tex]
c = [tex]\sqrt{(x-2)^{2}+(y-(-1))^{2} }[/tex]
Solving, a+b+c = 16
and using area equation we get
x = -6
y = 2