What is the distance between the point (3,6) and (-2,-3) in the xy plane?

You can use Pythagorean theorem; x^2 + y^2 = h^2.
x : the length of x-side
y : the length of y-side
h : the hypotenuse, which is the distance you seek
The length of x-side is 3+2=5, the length of y-side is 6+3=9 (there are no negative values, just add the values of x-points and y-points).
Then the distance must be: h^2 = 25 + 81 = 106.
h=10,296