program zB3_3;
uses crt;
const t=0.01; {tochnost' sravneniya veshestvennih chisel}

function Plosh(x1,y1,x2,y2,x3,y3:real):real;{ opredelenie ploshadi}
 begin
  Plosh:=abs((x1-x2)*(y3-y2)-(y1-y2)*(x3-x2))/2;
 end;

var x1,y1,x2,y2,x3,y3,tx,ty,s:real;

begin

clrscr;
 writeln('Vvedite koordinati vershin treugolnika:');
 writeln('Vershina 1:');readln(x1,y1);
 writeln('Vershina 2:');readln(x2,y2);
 writeln('Vershina 3:');readln(x3,y3);

if Plosh(x1,y1,x2,y2,x3,y3)<t then
write('Eto ne treugolnik!')
else
 begin
  writeln('Vvedite koordinati tochki:');
  readln(tx,ty);
  s:= Plosh(x1,y1,x2,y2,tx,ty)+ Plosh(x1,y1,tx,ty,x3,y3)+ Plosh(tx,ty,x2,y2,x3,y3);
  if  abs(Plosh(x1,y1,x2,y2,x3,y3)-s)<t then
   write('Tochka prinadlegit treugolniku!')
  else write('Tochka ne prinadlegit treugolniku!');
 end;
readln
end.