We come across many circular objects in our daily life. Let us know about a circle and explore other related terms. We shall also see some of the properties of a circle.

A circle is the locus of a point equidistant from a fixed point in a plane. In other words, *a circle is a collection of all the points in a plane, which are at a fixed distance from a fixed point.* The* fixed point *is called the centre of the circle and the *fixed distance *is called the radius of the circle.

The line segment joining any two points on a circle is called a chord. The chord which passes through the centre is called a diameter of the circle. The length of a diameter of a circle is twice the length of its radius.

A piece of a cirlce between two points is called an arc of the circle. The shorter arc is called the minor arc and the longer one is called the major arc.

A diameter divides a circle into two semi circles.

The length of the complete circle is called its circumference.

A circle divides a plane into two parts. One is the interior and the other is the exterior. A circle together with its interior is called the circular region.

A diameter divides the circular region into two semi circular regions.

The part of the circular region bounded by two radii and the corresponding arc is called a sector. The smaller one is called the minor sector and the larger one is called the major sector.

A chord divides a circular region into two segments. The smaller one is called the minor segment and the larger one is called the major segment.

Can a segment be a sector? Yes! A semicircular region is a segment which is also a sector.

The angle subtended by an arc at the centre is called the central angle. The central angle of an arc is twice the angle subtended it in the alternate segment.

A quadrilateral whose vertices lie on a circle is called a cyclic quadrilateral. Opposite angles of a cyclic quadrilateral are supplementary.

Equal chords of a circle are equidistant from the centre of the circle. Equidistant chords of a circle from its centre are equal in length.

Choose the correct option from the brackets to fill up the blanks.

1. A line segment joining the centre to a point on the circle is called __________ (radius/diameter)

2. A line segment joining two points on a circle is a_______(chord/ diameter)

3. The centre of a circle is in the _________ (interior/exterior)

4. The longest chord of a circle is ________(radius/diameter)

5. Diameter is _____________( half the radius/double the radius)

6. A piece of a circle between two points on the circle is ______(chord/arc)

7. The shorter arc of a circle is called _______ (minor arc/major arc)

8. The length of the complete circle is called its _______ ( area/circumference)

9. The region between a chord and its arc is called______( sector/segment)

10. The region between two radii and the corresponding arc is called a ________(sector/segment)

Hope you enjoyed this simple lesson on circles.