CIRCLES

                                                                CIRCLES

INTRODUCTION

A circle is a 2-dimensional closed shape that has a curved side whose ends meet to form a round shape. The word ‘Circle’ is derived from the Latin word 'circulus' which means a small ring. Let us learn more about the circle definition, the circle formulas ,and some daily life examples.

                      Circle Definition

A circle is a closed two-dimensional figure in which the set of all the points in the plane is equidistant from a given point called “center”. Every line that passes through the circle forms the line of reflection symmetry. Also, it has rotational symmetry around the center for every angle. The circle formula in the plane is given as:

(x-h)2 + (y-k)2 = r2

where (x,y) are the coordinate points
(h,k) is the coordinate of the center of a circle
and r is the radius of a circle.

SOME DAILY LIFE EXAMPLES OF CIRCLES

There are many objects we have seen in the real world that are circular in shape. Some of the examples are:

• Ring
• CD/Disc
• Bangles
• Coins
• Wheels
• Button
• Dartboard
• Hula hoop

We can observe many such examples in our day to day life.

Parts of Circle

• Arc – It is basically the connected curve of a circle.
• Sector – A region bounded by two radii and an arc.
• Segment- A region bounded by a chord and an arc lying between the chord’s endpoints. It is to be noted that segments do not contain the centre.

See the figure below explaining the arc, sector and segment of a circle.

• Centre – It is the midpoint of a circle.
• Chord- A line segment whose endpoints lie on the circle.
• Diameter- A line segment having both the endpoints on the circle and is the largest chord of the circle.
• Radius- A line segment connecting the centre of a circle to any point on the circle itself.
• Secant- A straight line cutting the circle at two points. It is also called an extended chord.
• Tangent- A coplanar straight line touching the circle at a single point.

See the figure below-representing the centre, chord, diameter, radius, secant and tangent of a circle.

Area and Circumference of a Circle

to know about circles area and circumference click the following link area and circumference

Circumference (C)	The circumference of a circle is defined as the distance around the circle. The word ‘perimeter’ is also sometimes used, although this usually refers to the distance around polygons, figures made up of the straight line segment. A circle circumference formula is given by   C = πd = 2 π r Where, π = 3.1415
Area (A)	Area of a circle is the amount of space occupied by the circle. The circle formula to find the area is given by Area of a circle = πr2

here i conclude this chapter with the brief description of circles