Practice problem
Which Circles Are Congruent?
By Liza Sulkin
A red, a green, and a blue car race around a circular track of radius n. In the time it takes the red car to complete a lap, the green car completes two laps. The blue car, meanwhile, is traveling in the opposite direction of the other two cars; while it completes a lap, it is unclear in the end how long it took to do so.
Which (if any) of the cars' paths are congruent circles?