|The stupid question is the question not asked
This may be an academic example, but it's very weird to see you set the area of a circle.
I don't see that as weird at all. It's just the other side of the equation. If it seems weird to you, I'd guess that's because your math classes only taught you to think in one direction. If you'd seen R = sqrt(A/pi) printed inside the back cover of high school algebra textbook, this might not seem so strange.
-sauoq "My two cents aren't worth a dime.";