Question

The diameter of a circle is a line which joins two points on the circle and also passes through the centre of the circle. (In the adjoining figure AB is a diameter
of the circle, C is its centre.) Express the diameter of the circle (d) in terms of its
radius (r).​

Answer 1

Answer:

diameter (d)=2*(radius)

so,radius =diameter/2

Answer 2

The diameter of a circle is a line which joins two points on the circle and also passes through the centre of the circle.

Consider the attached figure while going through the following steps.

The diameter of the circle with center C is AB

⇒ d = AB

As given C is the center of the circle.

The diameter AB = AC + CB

⇒ AC = CB = AB/2

as the center divides the diameter into two equal halves.

So, we have,

AC = CB

The radius of the circle is given by,

r = AC = CB

⇒ r = AB/2

∴ r = d/2