program lab4_11v;
uses Crt;
const a = 0;
      b = 3;
      E = 0.001;

 function arcsin(x:real):real;
 begin
  if x=1.0 then
     arcsin := Pi/2.0
  else
     arcsin := arctan(x/sqrt(1-x*x));
 end;

 function f(x:double):double;
 begin
  f:= arcsin(sqrt(x/(1+x)));
 end;

 var
  S, h,n,M, x,Xn,I : double;

begin
 ClrScr;

 M := 0.05413; {max|f''(x)|}
 h := sqrt( (24*E) / ((b-a)*M) ); {krok}
 n := (b-a)/h; {4aCTuH}

 S := 0;
 x := a;
 repeat
 begin
     Xn := x+h;
      S := S + f((x+Xn)/2);
      x := Xn;
 end;
 until (Xn <= (b-h));

 I:= h * S;
 writeln('I = ',I:5:5);

 readln;
end.