8.992254284692088 is the radius I believe
The triangle inequality requires the third side be in the range
.. 12 -4 ≤ third side ≤ 12 +4
.. 8 ≤ third side ≤ 16 . . . . . . . . . your answer is the number(s) in this range
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Some define the triangle inequality using < rather than ≤. Be careful here.
The answer is A , because when you are finding the probability of an object , you are to divide the number of sides the object has which is 4 and put a 1 over the 4 , and you get 1/4