Question:
How many chords can be drawn through 21 points on a circle?
How many chords can be drawn through 21 points on a circle?
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To find number of chords from $n$ points on a circle, use combination $\binom{n}{2}$.
Updated On: May 18, 2025
- 105
- 210
- 420
- 840
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The Correct Option is B
Solution and Explanation
A chord is determined by 2 distinct points on the circle. So total number of chords is:
\[
\binom{21}{2} = \frac{21 \cdot 20}{2} = 210
\]
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