circle

     

Circles are simple shapes of Eucliean geometry. A circle consists of those points in a plane which are at a constant distance, called the radius, from a fixed point, called the center. A circle with center A is sometimes denoted by the symbol A.

Trivia about circle

  • It's an ellipse with an eccentricity of zero
  • To figure the ratio of its circumference to its diameter is as easy as pi
  • Its area equals pi r (squared)
  • Ladies who gather over needle & thread make up a sewing one of these shapes
  • The "henge" part of the word Stonehenge is a term meaning an ancient monument arranged in this shape
  • The ordinary conic sections are the hyperbola, the parabola, the ellipse & this
  • Ferdinand von Lindemann proved the problem of "squaring" this with compass & ruler was impossible
  • In plane geometry, a chord is a line segment connecting 2 points that lie on this shape
  • The saw, an ancient tool, was first patented in this shape by Samuel Miller in 1777
  • In the Old West, you did this to "the wagons" when there was an attack