1. The problem statement, all variables and given/known data Take a 3" X 5" notecard and fold it such that point A is on top of point B. Find the length of the crease algebraically. http://img527.imageshack.us/img527/9913/notecard.jpg [Broken] point C is a point created by me. the dotted line is the crease. the red line is point A to Point C. 2. Relevant equations none 3. The attempt at a solution i dont even know where to start i have realized that the distance from Point A to Point C(the red line in the diagram) is equal to Point B to Point C. But i dont know how to prove that algebraically, and i dont know how to find the length of the crease.