Circle

Circle:

• A Circle is a closed  figure in a plane and it is the collection of all those points in the plane,which are at a constant distance from a fixed point in the plane.

• The  fixed point is called the centre of the circle and the constant distance is called the radius of the circle.        
• There is one and only one circle passing through three given  points.

Angle subtended by an arc of a circle

• The angle subtended by an arc at the centre is double the angle subtended by it at any point on the remianing part of the circle.
• The angle subtended in a semicircle is aright angle.
• Angles in the same segment of a circle are equal.