Geometry or Formuls to construct a circle to three entities.

[Neale]

Thank you for your help, much appreciated. I'll try it out at work today.

I presume both the ^ and * symbols in the formula stand for squared?

"^2" means squared; "*" means multiplication. That's one reason why I didn't want to write out the derivation - too much chance of getting it wrong!

[Kitwn]

Nice to have an excuse to get the old geometric grey matter working! I've just turned to paper and pencil and come up with the same answer as Neale. I don't fancy trying to work out the option where the two blue circles are not symmetrical about the horizontal line though. That turns it into a two dimensional problem instead of just one.

Kit