Before I start, I apologise if the formatting is a bit unclear :/. Using the formula for the distance between two points (which is derived from the Pythagorean theorem) we get this:
d = √([8-1]²+[6-1]²) which simplifies to
d = √(49 + 25) = √74
If you put √74 in to a calculator, you can find that the distance is closest to 8.6 units.
