Calculate Triangle height Theorem

var
  Form1: TForm1;
  bm:tbitmap;
  a,b,c,d,q,h,w,x1,y1,x2,y2,x3,y3,x4,y4:real;
  dyn1,dyn2,i,ri:integer;
  dyn:boolean;
  
//

procedure TForm1.FormActivate(Sender: TObject);
begin
  bm:=tbitmap.create;
  dyn:=false;
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  bm.free
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  bm.Width:=paintbox1.Width;
  bm.height:=paintbox1.height;
  bm.canvas.Pen.color:=clwhite;
  bm.canvas.brush.color:=clwhite;
  bm.canvas.rectangle(0,0,bm.width,bm.height);

  if dyn=false then begin
    a:=strtofloat(edit1.text);
    b:=strtofloat(edit2.text);
    c:=bm.width/3;
    d:=sqrt(a*a+b*b);
    a:=a*c/d;
    b:=b*c/d;
    q:=a*a/c;
    h:=sqrt(a*a-q*q);
  end;

  x1:=(bm.width-c)/2;
  y1:=bm.height/2;
  x2:=(bm.width+c)/2;
  y2:=y1;
  x3:=x1+q;
  y3:=y1-h;
  x4:=x3;
  y4:=y1;

  if dyn=true then begin
    q:=i-x1;
    h:=sqrt(q*(c-q));
    x4:=i;
    x3:=i;
    y3:=y4-h;
  end;

  bm.canvas.Pen.color:=clblack;
  bm.canvas.MoveTo(round(x1),round(y1));
  bm.canvas.lineTo(round(x2),round(y2));

  w:=0;
    repeat
    bm.canvas.Pixels[round(bm.width/2+c/2*cos(w)),round(bm.height/2-c/2*sin(w))]:=clblack;
    w:=w+2/c;
    until w>=pi;

  bm.canvas.Brush.color:=clblue;
  bm.canvas.FloodFill(round(bm.width/2),round(bm.height/2-2),clwhite,fssurface);
  bm.canvas.Brush.color:=clyellow;
  bm.Canvas.Rectangle(round(x4),round(y4),round(x4+h),round(y4-h));
  bm.canvas.Brush.color:=clgreen;
  bm.canvas.Rectangle(round(x1),round(y1),round(x1+q),round(y1+(c-q)));
  bm.canvas.MoveTo(round(x2),round(y2));
  bm.canvas.lineTo(round(x3),round(y3));
  bm.canvas.lineTo(round(x1),round(y1));

  w:=0;
    repeat
    bm.canvas.Pixels[round(x4+(c-q)*cos(w)),round(y4+(c-q)*sin(w))]:=clblack;
    w:=w+1/(c-q);
  until w>=pi/2;

  bm.Canvas.Brush.color:=clwhite;
  bm.canvas.floodfill(round(x4-2),round(y4-2),clblue,fssurface);
  bm.canvas.floodfill(round(x4+h+1),round(y4-2),clblue,fssurface);
  bm.Canvas.brush.Style:=bsclear;
  bm.canvas.TextOut(round(x1-10),round(y1+4),'A');
  bm.canvas.TextOut(round(x2+4),round(y2+4),'B');
  bm.canvas.TextOut(round(x3-4),round(y3-14),'C');
  bm.canvas.TextOut(round(x4+2),round(y4+4),'F');

  paintbox1.canvas.draw(0,0,bm);
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  dyn:=not (dyn);

  if dyn=true then button2.Caption:='Simulation Aus'
            else button2.Caption:='Simulation An';
            timer1.enabled:=not (timer1.enabled);
            dyn1:=round(x1);
            dyn2:=round(x2);

  if dyn=true then begin
    i:=round(x1+q);
    ri:=1
  end;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  if i>=x2-1 then ri:=0;
  if i<=x1+1 then ri:=1;
  if ri=1 then inc(i)
  else
  dec(i);

  Button3Click(Sender);
end;