Ford Circle - History

History

Ford circles are a special case of mutually tangent circles; the base line can be thought of as a circle with infinite radius. Systems of mutually tangent circles were studied by Apollonius of Perga, after whom the problem of Apollonius and the Apollonian gasket are named. In the 17th century René Descartes discovered Descartes' theorem, a relationship between the reciprocals of the radii of mutually tangent circles.

Ford circles also appear in the Sangaku (geometrical puzzles) of Japanese mathematics. A typical problem, which is presented on an 1824 tablet in the Gunma Prefecture, covers the relationship of three touching circles with a common tangent. Given the size of the two outer large circles, what is the size of the small circle between them? The answer is equivalent to a Ford circle:

Ford circles are named after American mathematician Lester R. Ford, Sr., who wrote about them in 1938.

Read more about this topic:  Ford Circle

Famous quotes containing the word history:

    I believe my ardour for invention springs from his loins. I can’t say that the brassiere will ever take as great a place in history as the steamboat, but I did invent it.
    Caresse Crosby (1892–1970)

    While the Republic has already acquired a history world-wide, America is still unsettled and unexplored. Like the English in New Holland, we live only on the shores of a continent even yet, and hardly know where the rivers come from which float our navy.
    Henry David Thoreau (1817–1862)

    A man will not need to study history to find out what is best for his own culture.
    Henry David Thoreau (1817–1862)