You could always use fixed circles.

 

Construct the circumcircle with fixed circles only.

I already showed you how to construct the middle perpendicular. So you can find the midpoint U.

To get the circumcircle itself, create a fixed circle and set its size to the distance of U and A. This is similar as on the previous page, but you need to click two points after you exit the dialog with "Set size".

This ends the tutorial about fixed circles!