Angle at the centre of a circle by an arc

As performed in real lab:

Material Required

Colored papers, a pair of scissors, gum, compass, pencil, ruler, carbon paper or tracing paper.


  1. Draw circle of any radius and cut it using scissor.
  2. Take a rectangular sheet of paper and paste circle on it.
  3. Take two points A and B on circle and draw AO and BO, O is centre of circle.
  4. Take another point P on remaining part of the circle and draw AP and BP using ruler and pencil.
  5. Make two replicas of ∠APB and paste these replicas adjacent to each other on ∠AOB.

As performed in the simulator:

  1. Mark a point on the workbench area such that it forms radius for the circle with point O as the origin and length of the radius must be in between 2 to 5 cm.
  2. Mark any two points (A, B) on circle such that considerable distance is maintained between two points.
  3. Mark point P in remaining part of the circle to form ∠APB.
  4. Click on ∠APB to create replica.
  5. Click on both colored angles to rotate.
  6. Place both replica adjacent to each other on centre O .


  • The student will observe that two replicas of ∠APB completely covers ∠AOB.
  • ∠AOB=2*∠APB.

Process of Execution