Python / Language / Circle - https://www.minte9.com/python/language-loops-1250

circle.py

"""
Write a function called circle that takes a turtle, t, and radius, r, 
as parameters and that draws an approximate circle 
by calling polygon with an appropriate length and number of sides. 

Test your function with a range of values of r.

Hint: figure out the circumference of the circle 
and make sure that length * n = circumference.

import turtle

def poligon(t, length, n): 
    for i in range(n):
        t.fd(length)
        t.lt(360/n)

bob = turtle.Turtle()
poligon(bob, 20, 10)
turtle.mainloop() """


# SOLUTION

import turtle
import math

def poligon(t, length, n): 
    for i in range(n):
        t.fd(length)
        t.lt(360/n)

def circle (t, r):
    circumference = 2 * math.pi * r
    n = 360 # slow
    n = 36 # fast
    length = circumference/ n
    poligon(t, length, n)

bob = turtle.Turtle()
circle(bob, 50)
circle(bob, 100)
turtle.mainloop()