[SOLVED] how do I convert from one cartesian system to another

how do I convert from one cartesian system to another

2D problem: I measure the position of the 3 ends of a triangle in a cartesian system. Now i move the system (triangle) to another cartesian system and measure the position of just two ends. How can I identify the location of the 3rd end based on this data?

thanks! (and sorry for the bad english as a second angle)

Solution

This is a pretty vague question, but if I'm reading it right, then you need even less information than that. If you have the transformation of the first coordinate system to the second, then apply that to each of the three points to find each of the 3 equivalent points.

Otherwise, if you don't have the transformation, I would think it's impossible. After all, an infinite number of possible transformations of a coordinate system can result in the same two locations of two points yet different locations of the third.