Geometry

Question Analysis:
This question focuses on using the distance formula in coordinate geometry to find the length of a side of a triangle.
The main focus is on correctly substituting the coordinates of the two endpoints of the side into the distance formula.

Key Concept Explanation:
The distance formula between two points and is .
It is derived from the Pythagorean theorem and is used to calculate the length of line segments in the coordinate plane.

Step - by - Step Solution:
1. Identify the coordinates for points and :
  - For point , , . For point