The Pythgorean theorem is given by the following formula:
h² = a² + b²
where h is the hypotenuse and a and b are the legs of the right triangle.
In the given image, when you construct a ritgh triangle with the line of the two points as a hypotenuse, you have for a and b:
a = 5
b = 12
replace the previous values of a and b in the formula for h:
h² = (5)² + (12)²
h² = 25 + 144
h² = 169
h = √169
h = 13
Hence, the distance in betwee the two given points is 13 units
A drawing of the right triangle is shown below: