Thankyou for asking this question. It will always be true.
BA added to AC will always be equal to BC if the point A is between B and C.
This is because no matter what the distance from A to B and A to C is until and unless its between them it will make the total distance to be equal B + C.
In case A does not lie between B and C then the answer might change.
I hope my answer helps you in some manner.
