In the figure above, a coin is right up against the far edge of the mug. In picture (a) the coin is just hidden from view and in picture (b) we can almost see the whole coin. If the mug is 6.1 cm in diameter and 8.5 cm tall, what is the diameter of the coin?
http://d2vlcm61l7u1fs.cloudfront.net/media%2F6c6%2F6c6ea368-3b67-4f93-835d-051bf566a6a6%2FphpFJA3LO.png