Python几何编程算阴影面积

一个适合学了几何的简单程序.

import turtle

turtle.shape('turtle')
turtle.pensize(2)
turtle.speed(0)
turtle.color('gray')
turtle.setup(800,600)

turtle.bk(400)
turtle.fd(800)
turtle.bk(400)

turtle.left(90)
turtle.fd(300)
turtle.bk(600)

turtle.home()

turtle.begin_fill()
turtle.circle(100)
turtle.end_fill()

turtle.fillcolor('white')
turtle.begin_fill()
turtle.circle(100,360,3)
turtle.end_fill()

ft = ('黑体',14,'normal')
turtle.sety(-100)
s = '圆的半径是100，请问阴影部分面积是多少?'
turtle.write(s,align='center',font=ft)
turtle.ht()

turtle.done()