дз 2 часть 4 юнит

Unit INTG;
   Interface
      procedure INTG1(n: real; key: integer);
   Implementation
     procedure INTG1;
     function f(x: real): real;
begin
   if key = 1 then result := x + cos(x);
   if key = 2 then result := (sin(x + 1) / cos(x + 1)) / (x + 1);
end;
var a, b, s, delta: real;
begin
  s := 0;
  if key = 1 then begin
    a := -1; b := 4;
  end;
  if key = 2 then begin
    a := -1.5; b := 0;
  end;
  delta := (b - a) / n;
  s:=(f(a)+f(b))/2;
  while a<b do begin
    a := a + delta;
    s := s + f(a);
  end;
  s := s * delta;
  writeln('S = ', abs(s));
  end;
End.