def double_layer_cover_reflection_coefficient(transmission_coef_1, reflection_coef_1, reflection_coef_2) -> float:
    """
    The reflection coefficient
    Equation 8.15
    :param float transmission_coef_1: the transmission coefficients of the first layer
    :param float reflection_coef_1: the reflection coefficients of the first layer
    :param float reflection_coef_2: the reflection coefficients of the second layer
    :return: The reflection coefficient
    """

    return reflection_coef_1 + (transmission_coef_1 * transmission_coef_1 * reflection_coef_2) / (1 - reflection_coef_1 * reflection_coef_2)