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procedure Button1 (sender...)
begin
  if RadioButton1.clicked then form2.show
  if RadioButton2.clicked then form3.show
end;                    

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procedure Button1 (sender...)
begin
  if RadioButton1.checked then form2.show;
  if RadioButton2.checked then form3.show;
end;                    

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procedure TForm1.Button1Click(Sender: TObject);
begin
  if RadioButton1.Checked then
    begin
      Form2.Show;
    end
  else
    begin
      if RadioButton2.Checked then
        begin
          Form3.Show;
        end;
    end;
end;                    

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uses Unit2, Unit3;