import math
import random


def rand_cluster(n,c,r):
    """returns n random points in disk of radius r centered at c"""
    x,y = c
    points = []
    for i in range(n):
        theta = 2*math.pi*random.random()
        s = r*random.random()
        points.append((x+s*math.cos(theta), y+s*math.sin(theta)))
    return points