根据圆的半径计算内接外切正四边形

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Edit1: TEdit;
    Edit2: TEdit;
    Edit3: TEdit;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

function outsquare(r: integer): real;
function insquare(r: integer): real;

var
  Form1: TForm1;

implementation

{$R *.dfm}

function outsquare(r: integer): real;              //外切正四边形的面积
begin
  outsquare := 2*r*2*r;
end;

function insquare(r: integer): real;               //内接正四边形的面积
begin
  insquare := 2*r*r;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  radius: integer;                                 //圆的半径
begin
  radius := strtoint(Edit1.Text);                  //字符串转换为整数
  Edit2.Text := floattostr(insquare(radius));      //编辑框2为内接正四边形
  Edit3.Text := floattostr(outsquare(radius));     //编辑框3为外切正四边形
end;

end.

 

编辑框2和3的ReadOnly属性为True