What's wrong with a such solution?

Program p1232; {$N+}

Const Eps  = 1e-12;

Type Point = Record X,Y,Z : Extended End;

Var h,d,alpha  : Extended;
    Ans        : Array[0..1500]of Point;

Function IsCPoint(P : Point) : Boolean;
Var CurH,MaxD  : Extended;
 begin
  CurH:=h-P.Z;
  MaxD:=CurH*Sin(alpha/2)/Cos(alpha/2);
  IsCPoint:=Abs(P.X)<MaxD+Eps;
 end;

Function CanLPoint(HD : Extended; LP : Point; Var NP : Point) :
Boolean;
 begin
  NP.Y:=0;
  NP.Z:=LP.Z-HD;
  NP.X:=LP.X-sqrt(d*d-HD*HD);
  CanLPoint:=IsCPoint(NP);
 end;

Function CanRPoint(HD : Extended; LP : Point; Var NP : Point) :
Boolean;
 begin
  NP.Y:=0;
  NP.Z:=LP.Z-HD;
  NP.X:=LP.X+sqrt(d*d-HD*HD);
  CanRPoint:=IsCPoint(NP);
 end;

Procedure TryIt;
Var n,i         : Integer;
    curh,need   : Extended;
    L,R,M       : Extended;
    GLeft,GDown : Boolean;
 begin
  n:=Trunc(1+h/d-Eps);
  if d-Eps>h/Cos(alpha/2) then Exit;
  ans[0].X:=0;
  for i:=0 to n do ans[i].Y:=0;
  ans[0].Z:=h;
  GLeft:=True;
  GDown:=False;
  if (n*d+Eps>h) And (n*d-Eps<h) then GDown:=True;
  for i:=1 to n do begin
    if GDown then begin
      ans[i].X:=ans[i-1].X;
      ans[i].Z:=ans[i-1].Z-d;
      Continue;
     end;
    need:=ans[i-1].Z-(n-i)*d;
    if GLeft then begin
      L:=1e-7;
      R:=d;
      if R>ans[i-1].Z then R:=ans[i-1].Z;
      While R-L>Eps Do begin
        M:=(R+L)/2;
        if CanLPoint(M,ans[i-1],ans[i]) then R:=M else L:=M;
       end;
      if M<need then begin
        M:=need;
        GDown:=True;
       end;
      if Not CanLPoint(M,ans[i-1],ans[i]) then Exit;
      GLeft:=False;
     end else begin
      L:=1e-7;
      R:=d;
      if R>ans[i-1].Z then R:=ans[i-1].Z;
      While R-L>Eps Do begin
        M:=(R+L)/2;
        if CanRPoint(M,ans[i-1],ans[i]) then R:=M else L:=M;
       end;
      if M<need then begin
        M:=need;
        GDown:=True;
       end;
      if Not CanRPoint(M,ans[i-1],ans[i]) then Exit;
      GLeft:=True;
     end;
   end;
  Writeln(n);
  for i:=1 to n do Writeln(Ans[i].X:0:8,' ',Ans[i].Y:0:8,' ',Abs(Ans
[i].Z):0:8);
  Halt;
 end;

begin
 Read(h,d,alpha);
 TryIt;
 Writeln(-1);
end.