math210-4wk-4-discussion-circles

This week we learned about circles. With paper and pencil nearby, think about these questions before looking at the reference linked below. Given two circles, how many tangent lines can be drawn that are common to both, i.e. tangent to both circles? Do the radii of the circles change the answer? What other criteria could change the answer? Now look at page 7 of this useful formula sheet: Circle Definitions and Theorems. Does it match what you found? What other tidbits of information on this thorough formula sheet do you find useful, interesting, surprising, or confusing? .