ARML Power Round - 2
Let the taxicab distance between two points be defined by:
\[D_t = |x_2-x_1|+|y_2-y_1|\]
Let a taxicab circle be the set of all point that are equidistant (in taxicab distance) from a fixed point, referred to as the center of the taxicab circle.
A taxicab circle is what geometric shape?
This problem is not original, it comes from the ARML 2016 Power Round