We need to form a right triangle so we could use the Pythagorean Theorem.
The Pythagorean Theorem states that:
The Pythagorean Theorem applies to right triangles only. a and b are the side lengths of the legs while c is the length of the hypotenuse.
In a Cartesian plane the side lengths a and b are represented like this:
So the Pythagorean Theorem would be:
as (5, -1)
We substitute the values to the Pythagorean theorem:
Therefore the distance between points is