CLASS-8
INTRODUCTION OF CIRCLE

CIRCLE -

An image will be considered as a circle when it is a closed plane curve consisting of all points at the same (or constant) distance from the fixed point ‘O’ of the plane. The fixed point ‘O’ is called the centre of the circle and the constant distance of the points of the circle and the constant distance of the points of the circle from its centre will be known as the radius of the circle. In the given figure, let us consider ‘O’ is the centre of the circle and W, X, Y, & Z are the points on the circle.

So, OW = OX = OY = OZ = the radius of the circle = r 

A line segment joining the centre and a point on the circle is also will be considered as a radius. Thus, OW, OX, OY, and OZ are known as radii (plural of radius) of the circle.

The symbol for a circle is ⊙. Any three points on a circle can be used to name it. Thus the circle in the figure will be called ⊙ WXY, or ⊙WXZ, or ⊙WYZ, or ⊙XYZ. A circle with centre ‘O’ and radius ‘R’ is denoted by C (O, R).