Circles
1.0 Definition
1.0 Definition
A circle is the locus of a point which moves in a plane whose distance from a fixed point, called the centre of the circle, is always constant, called the radius of the circle.
Circumference: The curve traced by the moving point, $P$, is called its circumference which is equal to ${\text{2}}\pi {\text{r}}$, where $r$ is the radius of the circle.
Chord: The line joining any two points on the circumference is called a chord. As shown in figure $2$, $AB$ and $CD$ are chords.
Diameter: If any chord passing through its centre, it is called the diameter of the circle. It is equal to two times the radius of the circle i.e., $D=2r$. In figure $3$, $AB$ is the diameter of the circle.
