AB = 14.42
If you plot these points on a graph, they will not be in a straight line, so we'll need to do a little more math here. Draw a diagonal line connecting both points, and use this line as the hypotenuse, so you can draw a right triangle. Count the lengths of each side (except the long, diagonal line called the hypotenuse). Use the equation a^2 + b^2 = c^2 to find the length of side c.
Since side a is 8 units long, square it to get 64.
And side b is 12 units long, and if we square it we get 144.
64 + 144 = 208.
One last step. Now we need to find the square root of 208.
It is 14.42.
So, the distance between points a and b is 14.42 units.