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PROGRAM MENCARI LUAS LINGKARAN

Elemen yang kita butuhkan:
1. 4 buah edit
2. 3 buah button

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    lbl1: TLabel;
    lbl2: TLabel;
    lbl3: TLabel;
    lbl4: TLabel;
    edt1: TEdit;
    edt2: TEdit;
    lbl5: TLabel;
    btn1: TButton;
    btn2: TButton;
    lbl6: TLabel;
    edt3: TEdit;
    lbl7: TLabel;
    edt4: TEdit;
    btn3: TButton;
    procedure btn1Click(Sender: TObject);
    procedure btn2Click(Sender: TObject);
    procedure btn3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btn1Click(Sender: TObject);
var jari2:Real;
    phi:Real;
    luas:Real;


begin
  phi:=3.14;
  phi:=22/7;
  jari2:=StrToFloat(edt1.Text);
   luas:=phi*jari2*jari2;
   edt2.Text:= FloatToStr(luas);

end;

procedure TForm1.btn2Click(Sender: TObject);
begin
edt1.Clear;
edt2.Clear;
edt3.Clear;
edt4.Clear
end;

procedure TForm1.btn3Click(Sender: TObject);
var diameter:Real;
    phi:Real;
    luas:Real;
begin
phi:=3.14;
phi:=22/7;
diameter:=StrToFloat(edt3.Text);
luas:=1/4*phi*diameter*diameter;
edt4.Text:=FloatToStr(luas);
end;

end.

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