\begin{definition}[Definition:Circle/Chord]
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A '''chord''' of a circle is a straight line segment whose endpoints are on the circumference of the circle.
In the diagram above, the lines $CD$ and $EF$ are both '''chords'''.
Thus a '''chord''' is a line segment joining the endpoints of an arc of the circle.
Note that under this definition, the diameter itself is in fact a '''chord'''.
{{EuclidSaid}}
:''{{:Definition:Euclid's Definitions - Book IV/7 - Fitted Into Circle}}''
{{EuclidDefRefNocat|IV|7|Fitted Into Circle}}
\end{definition}