Problem 14 and problem 16 are missing the diagrams needed to answer the questions. Thankfully, there is enough info for me to answer problem 15, which I'll do so below.
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If we have a triangle with side lengths a,b,c then we can write this compound inequality
b-a < c < b+a
If we knew the value of a and b, then we can find a range for c.
In our case, a = 5, b = 12, c = n, so,
b-a < c < b+a
12-5 < n < 12+5
7 < n < 17
The value of n is between 7 and 17. The value of n cannot equal 7, and it also can't equal 17 either.
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Final Answer for problem 15 is choice C) 7 < n < 17
