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Triangle inequality Theorem, need to make a conclusion about AC
AB + AC = 5;  AC + BC = 4
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We are given these two equalities
    AB + AC = 5    (1)
    AC + BC = 4    (2)
Subtract (2) from (1)  (both sides).  The terms "AC" will annihilate, so we will get
    AB - BC = 5 - 4 = 1.    (3)
Due to triangle inequalities,
    | AB - BC | < AC  for any triangle ABC.
So, from (3) we conclude that
    1 < AC,  or  AC > 1.
ANSWER.  From the given equalities, the triangle inequalities imply AC > 1.
Solved.