Parts of a circle
Centre, radius, diameter, chord, segment, arc, sector and circumference are the different
parts of a circle.
Provision of a circular ring may enable the child to conceptualize the outer circumference
of a circle.
Further, when the child is constructing the circle by himself using the nail, thread and
stick all the parts of the circle will certainly be clear as the activity is performed by
the child himself. Paper folding exercise may also be adopted to teach these concepts.
(Refer the section on Creative Mathematics).
Tangent
A line which touches the outer circumference of a circle at one single point is called
the tangent. The idea of a tangent may be explained to the child with the assistance
of a circular ring along with a small wooden strip, by making it touch the outer
circumference of the ring at a single point.
From a point outside of a circle two tangents can be drawn
Place the circular ring on a table. Take two wooden strips of the same length and
arrange the strips in such a way that they form two tangents to the ring originating
from the same point. On exploration, the child will be able to understand that from a
point outside a circle two tangents can be drawn.
Tangents drawn from a point outside a circle are of equal length
The lengths of the two tangents drawn from a point outside a circle will always be of
equal length.
