First you need to graph the coordinate points to see the triangle.
Then you need to drop lines down on the graph to form right triangles and use Pythagorean Theorem.
The line of points -5,-1 and -2,3 measures 5 using Pythagorean theorem.
The line of points 6,-3 and -5,1 measures √125
The line of points 6,-3 and -2,3 measures 10 using Pythagorean theorem.
So...
5 + 10 = 15
15 + √125
