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Seven points lie on a circle. How many chords can be drawn by joining these points pairwise?
ATwenty one chords
BTwenty two chords
CForty two chords
DFourteen chords
Answer & Solution
Correct answer: A. Twenty one chords
1. A chord is fixed by its two endpoints, and their order does not matter.
2. So the count is the combinations of 7 things taken 2 at a time.
3. That is 7 times 6 divided by 2, which gives 21.
_Source: NCERT Class 11 Mathematics, Ch 6 'Permutations and Combinations'_
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