Answer: 2 units.
Step-by-step explanation: When you graph the points given, it gives you this shape in the image below. The hypotenuse (longest side of triangle) is found by doing the following:
a^2 + b^2 = c^2, where a and b are the legs (the other sides of the triangle) and c is the hypotenuse.
5^2 + 2^2 = 29.
√ 29 ≈ 5.38, and that is the length of the hypotenuse.
The shortest side is the bottom side, which is 2 units. Therefore, that is your answer.
Let me know if this is right! :)