Answer
$AB + BC \gt AC$ which implies that the shortest distance between points A and C is a straight line.
Work Step by Step
Let's consider any triangle ABC.
A straight line from point A to point C is along the side AC of the triangle.
Suppose that $AB + BC \leq AC$
This statement claims that a path from A to B and then from B to C could be equal to or shorter then the straight line path AC. Then a straight line would not be the shortest distance between points A and C. Clearly this does not make sense. Therefore, it is not possible that $AB + BC \leq AC$.
Therefore, $AB + BC \gt AC$ which implies that the shortest distance between points A and C is a straight line.
