Pascal - ничего сложного!=)

[nes@]

определить принадлежит ли точка D(a4;b4) треугольнику ABC? A(a1;b1),B(a2;b2),C(a3,b3)

[fenix-elite]

Вот код с cyberforum.ru

uses crt;
var x,y,x1,x2,x3,y1,y2,y3:real;
s,s1,s2,s3:real;
Begin
Clrscr;
writeln('Vvedite koordinaty treugolnika: ');
write('x1= ');read(x1);write('y1= ');read(y1);
write('x2= ');read(x2);write('y2= ');read(y2);
write('x3= ');read(x3);write('y3= ');read(y3);
write('Vvedite koordinaty tochki: ');
write('x= ');read(x);write('y= ');readln(y);
If (x1=x2) and (x3=x1) or (y1=y2) and (y2=y3)
then
write('Nevernye koordinaty treugolnika!')
else
begin
s:=1/2*abs((x2-x1)*(y3-y1)-(x3-x1)*(y2-y1));
s1:=1/2*abs((x2-x1)*(y-y1)-(x-x1)*(y2-y1));
s2:=1/2*abs((x-x1)*(y3-y1)-(x3-x1)*(y-y1));
s3:=1/2*abs((x2-x)*(y3-y)-(x3-x)*(y2-y));
If s1+s2+s3=s then writeln('Tochka v treugolnike! ')
else writeln('Vne treugolnika!');
end;
readkey;
end.