Definition of circle
When a line AB rotate by 360 degree taking center A, thus obtained figure is called circle.
A is called center of circle. A to any point on the circle joining is called radius, a line passing through the center of the circle is called diameter of circle and its value is 2 * radius.
The ratio between circumference to diameter is always constant and denoted by its value is or 3.14 approximately.
Circumference of circle
so circumference of circle (p)=
Area of circle formula
Area of circle=
We divide a circle in to many small sectors, thus the length of an arc is reached near about the length of chord.
Then merge them as below we have obtained a ractangle.
Length of Chord
Length of chord=
where 2a=lengh of chord
h= height of arc
r=radius of circle
length of arc= arc/oce=Angle in degree/360
Radion: If are is equal in length to the radious, then the angle for form are called radion.
Segment of a circle
chord AB of a circle divides the circular region into two part, each part is called a segment of the circle.
Sector of the circle– the area surrounded by an arc and the two radius joining the end point of the arc with the center is called a sector of the circle.
Concentric circle– two or more circles with the given centre are called concentric circle.