1. Drag point A and B to change the length of the arc ANB and the angle (α) subtended by it at the center

- observe changes in θ and β (angle subtended by arc ANB at point P and Q)

-Check the relation between α , θ and β? Drag point P anywhere in the circle and observe the changes.

2.Drag point A or B such that angle subtended by arc at the center become 180
(see that arc become circumference of semicircle) -Now check the measures of β and θ, check the measures at every point on the arc AMB

OBSERVATIONS:

-Angle in the semicircle is right angle

-Angle subtended by arc at center is double the angle by it at any point on the circle.