## Geometry:-

- Today in this article I will discuss on what is circle, centre of a circle, radius of a circle, diameter, chord, tangent, secant, sector, segment, along with some formulae related on circle.

## Circle:-

- A curve plane figure whose circumference consists of a large number of points which are equidistant from a fixed point is termed as circle. In the picture,"O" is a circle.

## Centre:-

- The fixed point which is equidistant from the other points in the circle is called centre of the circle. In the picture,"O" is the centre of the circle.

## Radius:-

- Any line which touches the circumstance and centre of a circle is called radius of the circle.It is denoted by 'r' In the picture, OA=OB radii of the circle "O"

## Diameter:-

- Any line which passes through the centre of a circle and meets the circumference is called diameter of the circle. It is denoted by 'd' . In the picture,"AB" is the diameter of the circle"O"

## Chord:-

"CD" is a chord of the circle "O"

### A line which don't pass through the centre of a circle but joins any two points on the circumference of the circle is called chord of a circle.In the picture,

## Tangent:-

- A line which touches a circle exactly one point externally is called tangent of the circle. In the picture, "EF" is a tangent at point "P"

## Secant:-

- A straight line which touches the circle at two distinct points towards its circumstances is known as secant of the circle. In the picture, "CD" is the secant of the circle.

## Arc:-

- Any curved portion of the circumference of a circle is called arc of the circle. when a chord touches inside a circle ,it always produces two arcs and they are namely major arc and minor arc.

## Sector:-

- The region enclosed by two radii and an arc inside the circle is called sector of the circle. There are two sectors in every circle and they are namely major sector and minor sector. In the picture, "AOB" is a minor sector of the circle "O"

## Segment:-

- The region which is cut by a chord or a secant is called segment of the circle. When a chord cuts a circle it produces the minor and major segment.In the picture, region cut by the chord "CD"is a minor segment of the circle "O"

## Relation between diameter and radius of a circle:-

- Answer:- Diameter=2× Radius of the circle

- or,

- d =2×r, where d= diameter of the circle and r= radius of the circle.

- Some formulae of circle:-

- Perimeter or circumstance of a circle= 2πr

- Where,

- r= Radius of the circle.

- π= pie =22/7 for the convenience of problems solve is taken.

- Area of a circle= πr²

- Length of arc=∅÷360×2πr

- Where,

- ∅= measurement of centre angle.

- π = Radius of the circle.

- Area of the minor sector=∅÷360° ×πr²

- Where,

- ∅=measure of angle of the minor sector.

- r= Radius of the circle.

- Area of the major segment= Area of the circle— Area of the minor sector.

- Area of the minor segment=
- r²/2(π∅/180°-Sin∅)

- Where,

- ∅=measure of angle of the minor segment

- r = Radius of the circle.

- Area of the major segment= Area of the circle—Area of the minor segment.

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## FREQUENTLY ASKED QUESTIONS:-

##
## How many radius can be drawn in a circle?

Answer: Infinite number of radius can be drawn in a circle.

## How many diameter can be drawn in a circle?

Answer:- Infinite number of diameters can be drawn in a circle.

##
How many lines can pass through a point?

Answer :-
Infinite lines can be pass through a point.

## What is the greatest chord of a circle?

Answer :- The greatest chord of a circle is its diameter.

##
Write two conditions of two congruent circles.

Answer:- The two conditions of two congruent circles are :-
(i) Radii form equal angles at the center.
(ii) Their radii are equal.

## What is the measure of a semicircle angle?

Answer:- The measure of a semicircle angle is 90°

## How many radius can be drawn in a circle?

Answer: Infinite number of radius can be drawn in a circle.

## How many diameter can be drawn in a circle?

Answer:- Infinite number of diameters can be drawn in a circle.

## How many lines can pass through a point?

Answer :- Infinite lines can be pass through a point.

## What is the greatest chord of a circle?

Answer :- The greatest chord of a circle is its diameter.

## Write two conditions of two congruent circles.

Answer:- The two conditions of two congruent circles are :- (i) Radii form equal angles at the center. (ii) Their radii are equal.

## What is the measure of a semicircle angle?

Answer:- The measure of a semicircle angle is 90°

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