Построить чертеж трапеции по заданным длинам сторон в delphi

unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, Menus, StdCtrls, Spin, ExtCtrls;
 
type
  TForm1 = class(TForm)
    SpinEdit1: TSpinEdit;
    SpinEdit2: TSpinEdit;
    SpinEdit3: TSpinEdit;
    SpinEdit4: TSpinEdit;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    Button1: TButton;
    Label5: TLabel;
    Label6: TLabel;
    ListBox1: TListBox;
    ListBox2: TListBox;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    Image1: TImage;
    procedure Button1Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.dfm}
 
procedure TForm1.Button1Click(Sender: TObject);
var a,b,c,d,P,m :integer;
    y,s,h:real;
 
begin
a:=strtoint(SpinEdit1.text);
b:=strtoint(SpinEdit2.text);
c:=strtoint(SpinEdit3.text);
d:=strtoint(SpinEdit4.text);
 
y:=(sqr(c)-sqr(d)-sqr(b-a))/(2*(a-b));
h:=sqrt(sqr(d)-sqr(y));
S:=(1/2*(a+b))/h;
ListBox1.Items.Add(FloatToStr(S));
P:=a+b+c+d;
ListBox2.Items.Add(IntToStr(P));
 
end;
 
procedure TForm1.Button3Click(Sender: TObject);
begin
ListBox1.Clear;
ListBox2.Clear;
end;
 
procedure TForm1.Button4Click(Sender: TObject);
begin
close;
end;
 
 
 
procedure TForm1.Button2Click(Sender: TObject);
begin
//Image1.Canvas.Rectangle(a,b,c,d);
end;
 
end.