uses CRT,DOS;
var x1,x2,x3,y1,y2,y3:real;
    A,B,C:real;
    D,E,F:Single;
begin
    clrscr;

    x1 := 0;
    y1 := -5;
    x2 := 10;
    y2 := 0;
    x3 := 10;
    y3 := 5;

    A := sqrt( sqr(x1-x2) + sqr(y1-y2) );
    B := sqrt( sqr(x2-x3) + sqr(y2-y3) );
    C := sqrt( sqr(x3-y1) + sqr(y3-y1) );
    if not ((A + B <= C) or (A + C <= B) or (B + C <= A)) then
    begin
        writeln('Ne treugolnik');
        ReadKey;
        exit;
    end;

    D := (x1-0) * (y2-y1) - (x2-x1) * (y1-0);
    E := (x2-0) * (y3-y2) - (x3-x2) * (y2-0);
    F := (x3-0) * (y1-y3) - (x1-x3) * (y3-0);
    if (((D >= 0) and (E >= 0) and (F >= 0)) or ((D <= 0) and (E <= 0) and (F <= 0))) then
    begin
        writeln('Nachalo koordinat prinadleshit treugolniku');
    end
    else
    begin
        writeln('Nachalo koordinat ne prinadleshit treugolniku');
    end;

    ReadKey;
end.