It's funny, I usually only think about circles this way when trying to construct mutually tangent circular arcs, because if you have one circle inside (or outsi

It's funny, I usually only think about circles this way when trying to construct mutually tangent circular arcs, because if you have one circle inside (or outside) the other, their arcs are tangent at the point where they touch. I used circles a lot when doing CADs because they let you measure all the points a certain distance away from a given point, so intersecting two of them lets you do a lot of construction, like finding the two possibilities for the center of a circular arc that passes through two points of a given radius, assuming that they're not too far apart for that to exist.