Arc of a circle

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

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?