geometry

Parts of a Circle

• Circle: To review, a circle is a coplanar figure consisting of all the points equidistant from a fixed point.
  
• Center: That fixed one point is called the center of the circle. Circles are named by naming the center.
  
• Radius: Any segment with one endpoint at the center of the circle and the other endpoint on the circle is a radius. (The plural of radius is radii.)
  
• Chord: Any segment whose endpoints lie on the circle is a chord.
  

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  Circle

  Diameter: Any chord that passes through the center of the circle is a diameter.