Точка и заданная область

if (x=>0)and(y=>(-(5*x+5)))and(y=>(-(x+5))) then

function s(x1:integer; y1:integer; x2:integer; y2:integer; x3:integer; y3:integer) : real;
var
l1,l2,l3,p : real;
begin
l1:=sqrt(sqr(x1-x2)+sqr(y1-y2));
l2:=sqrt(sqr(x2-x3)+sqr(y2-y3));
l3:=sqrt(sqr(x1-x3)+sqr(y1-y3));
p:=(l1+l2+l3)/2;
s:=sqrt(p*(p-l1)*(p-l2)*(p-l3));
end;
var
su,sun,sunn,suu : real;
x,y,x1,x2,x3,y1,y2,y3 : integer;
begin
writeln('Enter the coordinates of the triangle: ');
writeln('First: ');
readln(x1);
readln(y1);
writeln('Second: ');
readln(x2);
readln(y2);
writeln('Third: ');
readln(x3);
readln(y3);
writeln('Enter the coordinates of point: ');
readln(x);
readln(y);
su:=s(x1,y1,x2,y2,x3,y3);
sun:=0;
sun:=sun+s(x,y,x1,y1,x2,y2);
sun:=sun+s(x,y,x1,y1,x3,y3);
sun:=sun+s(x,y,x2,y2,x3,y3);
if abs(sun-su)<0.0000001 then writeln('The point belonges to the triange.')
          else writeln('The point does not belong to the triangle');
readln;
end.

var
x,y:real;
readln(x,y);
if (x>=0)and(y>=-5*x+5)and(y<=-x+5)then writeln('yes')else writeln('no');
readln;
end.