A circle is a shape that is round.
It has infinite lines of symmetry through the centre of the circle.
To find the area and circumference of a circle, use these formulae:
A circle has many relationships between its angles.
Angles Subtended on the Same ArcEdit
Angle in a Semi-CircleEdit
Angle at centreEdit
The angle formed at the centre of the circle by lines originating from two points on the circle's circumference is double the angle formed on the circumference of the circle by lines originating from the same points. i.e. a = 2b.
The area of a sector =