Definition:Diameter of Circle
A line segment which passes through the centre of circle and whose end points fall on the circumference of the circle is called Diameter of Circle. And all such lines are always of equal length.
In the following figure.
Line segment AB, PQ, XY, RS all pass through the centre point “O” and meets circumference at point A & B, P & Q, X & Y, R& S respectively, hence will be referred as Diameters of Circle of circle and are of equal length.
Diameter is always twice of Radius, so formula to find diameter is :
d = 2r (here d = diameter and r = radius)
Lets solve following example and learn How to find diameter if radius is given.
Find the diameter of following circles
Radius (r) = 2 cm
Diameter (d) = 2r = 2 X 2 = 4 cm
Radius (r) = 1 cm
Diameter (d) = 2r = 2 X 1 = 2 cm
Radius (r) = 4 cm
Diameter (d) = 2r = 2 X 4 = 8 cm
Radius (r) = 3 cm
Diameter (d) = 2r = 2 X 3 = 6 cm

