import math


def param_to_angle(ratio: float, param: float) -> float:
    """Returns circle angle from ellipse parameter for argument `angle`.

    Args:
        ratio: minor axis to major axis ratio as stored in the ELLIPSE entity
            (always <= 1).
        param: ellipse parameter between major axis and point on the ellipse
            curve

    Returns:
        the circle angle in the range [0, 2π)
    """
    return math.atan2(math.sin(param) * ratio, math.cos(param))