 # Circles Class 9 CBSE Math Notes: Chapter 10

CBSE class 9 math notes for circles provided here will help students study everything about the concept from properties of a circle to other related terms. In these notes, students will also find important theorems, questions, and exercises which will be extremely helpful in preparing for the exam. Students will find some of the topics discussed in the chapter below;

• Definition of a circle.
• Related terms like Chord, Diameter, Circumference, Arc, Sector, Radius, and Segment.
• Important Questions.

## What is a Circle?

Generally, a circle is known to be a closed curved shape. However, going by its definition a circle is a plane figure, which is formed by the set of different points which are equidistant from a fixed point called the centre of the circle in the same plane. In general the equation of a circle in x,y quadrant is given as; ### Related Terms

Chord

A chord of a circle is basically the straight line that can be drawn by connecting the two ends of the arc line segment on the circumference of a circle.

Diameter

Diameter is nothing but the line that passes through the centre of a circle.

Arc

An arc is a connected curve or one of the portions of a circle. If the length of an arc is exactly half of the circle, it is known as a semicircular arc. An Arc is named based on its endpoints.

Annulus

An annulus is the region limited by two concentric circles and is usually referred to a ring-shaped object.

The radius of a circle is a line segment that connects the centre of a circle to any other point on the same circle. It is usually the fixed distance from the centre.

Sector

A sector is the part of a disk enclosed by two radii and an arc. A sector divides the circle into two regions called minor (smaller area ) and major (region having greater area) sector.

Segment

A region bounded by a chord and a corresponding arc lying between the chord’s endpoints is known as the segment of a circle. It is to be noted that the segments do not contain the centre point.

#### Theorems

Some of the theorems of circles are given below. ##### Important Questions We at Byju’s are providing circles class 9 maths notes here to help students get familiar with the concepts and solve problems easily.