import math


def circlePoints(x, r, cx, cy):
    """Ther dunction returns the y coordinate of a 
    circonference's point
    
    :x: x's coordinate value.
    :r: length of the radius.
    :cx: x coordinate of the center.
    :cy: y coordinate of the center."""
    
    return math.sqrt(math.pow(r,2) - math.pow(x-cx, 2)) + cy