The area affected was five hundred kilometres across, and perfectly circular.

This seems as close to perfectly circular as a real circle can be.

The third shot slammed into the door, blowing a perfectly circular hole in it.

From the sky above Area 7, it looked as if a perfectly circular earthquake had struck the facility.

It does not have to be perfectly circular, and some unevenness can improve the game.

It extended from right at ground level up to about ten feet and was perfectly circular.

It was perfectly circular, as far as she could see, like a sculpture.

It appeared perfectly circular, perhaps twenty feet high and three hundred or more in diameter.

A small, perfectly circular hole had appeared in the center of the wait and it was expanding.