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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def circos_radius(n_nodes, node_r):
 """ Automatically computes the origin-to-node centre radius of the Circos plot using the triangle equality sine rule. a / sin(A) = b / sin(B) = c / sin(C) :param n_nodes: the number of nodes in the plot. :type n_nodes: int :param node_r: the radius of each node. :type node_r: float :returns: Origin-to-node centre radius. """

    A = 2 * np.pi / n_nodes  # noqa
    B = (np.pi - A) / 2  # noqa
    a = 2 * node_r
    return a * np.sin(B) / np.sin(A)