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For questions concerning circles. A circle is the locus of points in a plane that are at a fixed distance from a fixed point.

A circle is a shape in geometry, defined as the locus of points that have a fixed distance from a fixed point, called the centre. The fixed distance from the centre of a circle to any of its points is called the radius. The length of the set of points is called the circumference, and for Euclidean space is related to the length of the radius by:

\begin{equation}\text{circumference}=2\pi\times\text{radius}\end{equation}

Similarly, in Euclidean space the area of a circle is given by:

\begin{equation}\text{area}=\pi\times\text{radius}^2\end{equation}

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