turtle写的圆的内接正多边形代码运行不了

import turtle as t
r=200
from math import sin,cos,pi
def Dbx(n):
a=2rsin*(pi/n)
t.seth(180/n)
for i in range(n):
t.fd(a)
t.lf(360/n)
s=input("n=")
n=int(s)
t.circle(r)
Dbx(n)
t.done()

import turtle as t

r = 200
from math import sin, pi


def Dbx(n):
    a = 2 * r * sin(pi / n)
    t.seth(180 / n)
    for i in range(n):
        t.fd(a)
        t.left(360 / n)


s = input("n=")
n = int(s)
t.circle(r)
Dbx(n)
t.done()

import turtle

T = turtle.Turtle()

T.circle(100)

T.circle(100, 360, 5)

turtle.done()