Parts of a circle
A chord is a straight line joining two points on the circumference of a circle.
An The curve between two points on the circumference of a circle. is a part of the circumference of a circle.
A segment is an area enclosed by a chord and an arc.
A sector is an area enclosed by two The distance from the centre of a circle to its circumference. The plural of radius is radii. and an arc.
A tangent is a straight line which touches the edge of a circle once.