American Flag Python Project

This is a project for extra credit in which we have to draw an american flag using python.  I have a decent start but am stuck and would like some help.  here is my code so far.

import turtle
math import sin, sqrt, radians

showturtle()
def star(width):
R = (width)/2*sin(radians(72))
A = (2*width)/(3+sqrt(5))

penup()
left(18)
penup()
forward(R)
pendown()

left(162)
forward(A)
right(72)
forward(A)

left(144)
forward(A)
right(72)
forward(A)

left(144)
forward(A)
right(72)
forward(A)

left(144)
forward(A)
right(72)
forward(A)

left(144)
forward(A)
right(72)
forward(A)

penup()
left(180-18)
penup()
forward(R)
penup()
left(180-18)
pendown()
showturtle()
star(500)