2 CIRCLE A circle is a simple shape consisting of those points in a plane which are at the same distance from a given point called the centre.
The common distance of the points of a circle from its center is called radius.
The diameter is a line segment that connects two points on the circle and goes through the center of the circle. It is always twice as long as the radius.
A chord is any line segment whose endpoints are at any two points on the circle and it doesn’t pass through the centre.
6 TANGENT The Tangent is a line which touches the circumference at only one point. A tangent is always perpendicular to the radius.
A secant is an extended chord: a straight line cutting the circle at two points.
A segment is a region bounded by a chord and an arc lying between the chord's endpoints
9 CIRCUMFERENCE OF A CIRCLE CircumferenceThe circumference of a circle is merely the boundary of the circle or rather its perimeter. It’s defined as: C = 2 × π × r where: C = Circumference, r = radius, and π = 3.1415 ....
10 SECTOR OF A CIRCLE A circular sector or circle sector, is the portion of a circle enclosed by two radii and an arc, where the smaller area is known as the minor sector and the larger being the major sector. Its formula is: Converting the central angle into degrees gives: x/360.TT r2
11 AREA OF A CIRCLE The area of a circle (the region occupied by a circle) is π r2 when the circle has radius r. Here the symbol π (Greek letter pi) denotes the constant ratio of the circumference of a circle to its diameter.
12 SOME FORMULAS RELATED TO CIRCLE
Diameter = 2 x radius of circle
Circumference of Circle = 2 π x radius where π = = 3.141592...
Area of Circle: area = π r2
Length of a Circular Arc: (with central angle ) if the angle is in degrees, then length = x (π/180) x r
Area of Circle Sector: (with central angle ) if the angle is in degrees, then area = (/360) π r2