The sides must be long enough to make a triangle. (If the sides are not long enough, they won't meet, so cannot form a triangle.)
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If your version of the triangle inequality includes the "or equal to" case, then the segments must be long enough to meet, even though the result may look like a line segment.
This would be a binomial model, since there is a fixed number of trials, the probabilities are independent and there are only two choices (either the shot is made or missed).
