Parts of Circle

Radius: It is a straight line from the centre of the circle to any point on its circumference.

Diameter: It is a straight line, that passes through the centre of a circle, between any two points on its circumference.

Chord: It is a straight line between any two points on its circumference.

Tangent: It is a straight line that touches the circle at exactly one point on its circumference.

Semicircle: It is half of a circle or half of its circumference.

Arc: It is a part of the circumference of a circle.

• Major Arc (more than half of its circumference)
• Minor Arc (less than half of its circumference)

Segment: It is a part of a circle that is enclosed by an arc and a chord of the circle.

• Major Segment (more than half of the circle)
• Minor Segment (less than half of the circle)

Sector: It is a part of a circle that is enclosed by an arc and two radii of the circle.

• Major Sector (more than half of the circle)
• Minor Sector (less than half of the circle)

Below shows a circle, with centre O.
The points A, B, C and X are points on the circumference of the circle.

You can:

• shift the point O to change the position of the circle
• shift the point X to change the size of the circle

To learn more about the various parts of a circle:

• check and uncheck the boxes
• shift the points A and B to change their positions

Note: To see the animation, click on the "play" button (at bottom left).



Download the GeoGebra file: http://www.geogebratube.org/material/download/format/file/id/41189