Video: The Relation between Radius and Diameter

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

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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.

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