Taxicab and Euclidean geometry differ a great deal, due to the modified metric function:

d_{T}(A, B) = |x_{a} - x_{b}| + |y_{a} - y_{b}|

(Note that this means when measuring distance, it is not the length of the hypotenuse, but the sum of the legs of the same right triangle.)

## My Main Problem

In *Euclidean* geometry, the answer to the question "Find the locus of points X such that: d(X, A) = 2 * d(X, B)" yields a regular, Euclidean circle. A little bit of algebra makes this very trivial.

But what is the answer to the *same* problem, but for d_{T}?

## What I Know So Far

This kind of geometry actually has a very interesting property, namely that as things rotate, their measures change. Consider the cases where points share either one of their coordinates. Many times, those situations yield the same answers as do their Euclidean counterparts.

Some things are noticeably different, though. For instance, a circle, as defined as the set of points a fixed distance from one point, actually comes out as a square, rotated 45 degrees. It is also trivial to illustrate that.

It *did* occur to me that the answer to this problem could be analogous to Euclidean geometry, and the solution may simply be a Taxicab circle (a square). But this didn't seem to work out. Plus, I worked out the solution for the points sharing an x or y coordinate, I end up with two mirror-image line segments. But the general case, where the two points are corners of any rectangle still eludes me. My second educated guess was that the solution could be a *Euclidean* circle, but this didn't work out either.

Lastly, *some* constructions seemed to differ depending on whether the points I chose formed the opposite diagonal corners of a general rectangle, or a square. E.g. (0,0) and (3, 3) seem to be a yet different type of exception.

Any thoughts on this problem would be greatly appreciated!