circles

• Parts of a circle


  • arc
  • sector
  • segment
  • chord
  • radius
  • diameter
  • tangent
• a radius is a strait line from the centre of the circle to the circumference.
• a chord is a strait line which endpoints that lie on the circumference.
• a tangent is a strait line that intersects the circle at exactly one point.
• the sum of the opposite angles of a cyclic quadrilateral is 180.