(Hint: Try using Pythagoras' Theorem).
I just went to search online,
they said a is the left right distance, b is the front back distance and c is the up down distance.
I understand why a^2 + b^2 + c^2 = d^2 but then shouldn't a be -1, b be -1, and c be 2?
How did you know sqrt 14 is the distance? The more I look at the diagram, it looks like the midpoint!