Diameter - GCSE Maths Definition
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What is a diameter?
In GCSE Maths, a diameter is a line that goes through the centre of a circle and whose ends touch the circumference at two different points. A diameter is a line of symmetry of a circle, as it cuts a circle exactly into two halves.
It is useful to remember that a diameter is twice the length of a radius for a circle. The diameter can be used to calculate the area or circumference of a circle, as well as having other applications in areas such as circle theorems.
Diameter Revision Resources to Ace Your Exams
Diameter is covered in our revision notes on 2D & 3D Shapes from GCSE Maths. You can also have a go at our related exam questions and flashcards to test your understanding. Don’t forget to check out the past papers for more general exam revision.
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