The circumcenter (C) is the point that is equidistant from the three vertices of a triangle. That sounds like a “center” for a triangle, doesn’t it? Let’s have a look:
Now let’s move one of the vertices and see what happens to C.
Let’s move the vertex way out and see what happens:
It seems like deciding on what “center” should mean is actually pretty hard. If you want to play with the circumcenter then click here.