RELATION BETWEEN THE ANGLE AT THE CENTRE & ANGLE AT THE CIRCUMFERENCE
* For ANIMATION , press PLAY BUTTON in the left bottom corner.
* As value of angle is rounded to nearest integer, at times there is a difference of 1 degree in the value of angle.
* Angle subtended by the same arc( or chord) at the centre is twice the angle at the circumference in a circle.
OR, the angle subtended at the circumference is half of the angle at the centre.