Answer:
Always.
Explanation:
If a point lies in between two end points of a line then the sum of distance between the points in between is always equal to the whole line.
If A is in between two points B and C then the sum of line segments BA and AC will always equal to the length of BC.
Or BA+AC=BC in all cases whatever be the position of point A between the points Band C.
Always is the right option.