\input zb-basic
\input zb-matheduc
\iteman{ZMATH 2009f.00475}
\itemau{Bergsten, Christer}
\itemti{Twin circles. (Tvillingcirklar.)}
\itemso{Normat. 57, No. 1, 22-31 (2009).}
\itemab
Summary: This ties in with previous articles on the arbelos of Archimedes, but instead of starting with two tangent circles, enclosed in a common tangent circle, no conditions are imposed on the two. We then get two cases, whether the circles intersect or not, and a detailed study is made of the ensuing circles. Much of the motivation for this paper is how the problems can be used to illustrate the power of various dynamical geometry software.
\itemrv{~}
\itemcc{G70 G50}
\itemut{arbelos; geometrical constructions; analytic geometry}
\itemli{}
\end