Diameter and radius
Click to explore updated revision resources for GCSE Maths: Parts of a circle, with step-by-step slideshows, quizzes, practice exam questions, and more!
The diameter of a circle is the distance from one side of a circle to the other through the centre.
The radius is the distance from the edge of the circle to the centre.
The diameter is twice as long as the radius.
Example
The pizza has a radius of 16 cm. What is the diameter?
\(16 \times 2 = 32~\text{cm}\)
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