You can
put this solution on YOUR website!Use Pythagoras' Theorem

for right-triangles, where d is the distance between the two points, x is the distance along the x-axis and y is the distance along the y-axis.
The change in x is equal to

which is

.
The change in y is equal to

which is

Now use Pythagoras:
Just like that!
I hope this helps.
P.S. I am trying to start up my own homework help website. I would be extremely grateful if you would e-mail me some feedback on the help you received to adam.chapman@student.manchester.ac.uk
Adam