Circle : A circle is the locus of a point which moves in a plane in such a way that its distance from a fixed point always remains same. The fixed point is called the centre and the given constant distance is known as the radius of the circle.

If r is the radius of a circle, then

(i)  Circumference  = 2πr or πd ,

where d = 2r is the diameter of the circle.


(iii) Area of semi circle

(iv) Area of quadrant of a circle