Arc of a circle

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The part of the circumference within the two points in either directions are called its arcs.

Arc.jpg

Objectives

  • The students learn that an arc is a part of a circle included between two distinct points on the circumference of the circle.
  • The students learn that the the larger arc is called major arc and the smaller one is called minor arc.

Estimated Time

10 minutes

Prerequisites/Instructions, prior preparations, if any

  • The students should know to draw a circle using compass.
  • They should know that arc is part of the circumference.

Materials/ Resources needed

  • Digital : Computer, geogebra application, projector.
  • Non digital : Worksheet and pencil, compass, strings
  • Geogebra files : Arcs in a circle .ggb

Process (How to do the activity)

    • If the circle is divided into 2 parts?
    • How many arcs are formed?
    • Are the two arcs equal?
    • Establish minor arc(smaller arc) and major arc(larger arc)
    • Compare region enclosed by major arc and minor arc, which is larger?
    • Establish sector – major sector and minor sector
    • Animate the geogebra file to show a major arc becomes a minor arc.
    • If one is major arc, the other is a minor arc; can the two arcs be equal?What are they called?
    • How are the two points with respect to center of the circle when arcs are equal.
    • If the angle between the radii is fixed but radius of the circle is increased, what can you say about the two arcs?
  • Evaluation
  1. What is the longest arc of a circle called?
  2. What are the arcs called when both major and minor arcs are of same size?