x_(M)=(x_(B)+x_(C))/2 ⇒ x_(C)=2x_(M)-x_(B)=2*(-2)-(-1)=-3
y_(M)=(y_(B)+y_(C))/2 ⇒ y_(C)=2y_(M)-y_(B)=2*(-2)-(-2)=-2
z_(M)=(z_(B)+z_(C))/2 ⇒ z_(C)=2z_(M)-z_(B)=2*0-2=-2
AB=sqrt((-1-(-1))^2+(-2-(-2))^2+(2-0)^2)=2
BC=sqrt((-3-(-1))^2+(-2-(-2))^2+(-2-2)^2)=sqrt(20)=2sqrt(5)
AC=sqrt((-3-(-1))^2+(-2-(-2))^+(-2-0)^2)=sqrt(8)=2sqrt(2)
P_( Δ ABC)=AB+BC+AC=2+2sqrt(5)+2sqrt(2)