def getTriangleCentroid(x1, y1, x2, y2, x3, y3):
    """
    Return the x and y coordinates of a triangle's centroid.

    Parameters
    ----------
    x1 : float
        x coordindate of first point defining a triangle
    y1 : float
        y coordindate of first point defining a triangle
    x2 : float
        x coordindate of second point defining a triangle
    y2 : float
        y coordindate of second point defining a triangle
    x3 : float
        x coordindate of third point defining a triangle
    y3 : float
        y coordindate of third point defining a triangle

    Returns
    -------
    x : float
        x coordinate of triangle's centroid
    y : float
        y coordinate of a triangle's centroid

    """

    x = (x1 + x2 + x3) / 3.0
    y = (y1 + y2 + y3) / 3.0

    return x, y