If 20 points are marked on a circle, how many chords can be drawn… - Vidyadip

Question

If 20 points are marked on a circle, how many chords can be drawn?

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Answer

To draw a chord we need to join two points on the circle. There are 20 points on a circle.
$
\begin{aligned}
& \therefore \text { Total number of chords possible from these points }={ }^{20} \mathrm{C}_2 \\
& =\frac{20 !}{2 ! 18 !} \\
& =\frac{20 \times 19 \times 18 !}{2 \times 1 \times 18 !} \\
& =190
\end{aligned}
$

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