### Video Transcript

The length of the radius of a
circle is what the length of its diameter.

Remember, the radius of a circle is
the straight line that joins the point at the center to any point on the
circumference of the circle. So, if we take a circle whose
center is 𝑜, we could have a radius here. And what about the diameter? Well, the diameter also passes
through the center of the circle. But this time, it’s a straight line
that joins two points on the circumference. So, the diameter of this circle is
this line here.

But of course, If we look carefully
at the diameter, we can see that we can make up of one, two radii. And so, this means that a diameter
of the circle must be twice or double the length of the radius. And in turn, we can say that the
radius of the circle must therefore be half the length of its diameter.