**Circle Geometry** deals with the measurements and relationships of lines and angles of a circle.

Let’s recap what we have learnt previously:

A circle is the locus of points in a plane that are a fixed distance (the radius) from a fixed point (the centre).

Any line extending from the centre O to any point on the circumference or bounding surface is called a **radius**. Any two radii have the same length.

**Note: **The plural form of radius is radii

The **chord** of a circle is defined as the line segment joining any two points on the circumference of the circle.

A** diameter** is a chord that passes through the centre of the circle and divides the circle into two equal parts. A diameter consists of two radii joined at their endpoints, therefore, the length of a diameter is twice the radius.

If a chord is not a diameter it divides the circle into two unequal parts, the major segment and the minor segment.

### Properties of the Chord of a Circle:

Some important properties of chords of a circle are given below;

**(i) **A straight line which joins the centre of a circle to the midpoint of a chord, that is not a diameter, is perpendicular to the chord.

**(ii) **A chord when extended infinitely on both sides becomes a secant

**(iii)** A chord that is not a diameter divides the circle into two segments, the major segment and the minor segment.

**(iv) **Chords of a circle, equidistant from the centre of the circle are equal.

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