JEE Mains · Maths · STD 11 - 6. permutation and combination
Suppose that \(20\) pillars of the same height have been crected along the boundary of a circular stadium. If the top of each pillar has been connected by beams with the top of all its non-adjacent pillars, then the total number of beams is
- A \(210\)
- B \(180\)
- C \(170\)
- D \(190\)
Answer & Solution
Correct Answer
(C) \(170\)
Step-by-step Solution
Detailed explanation
Total cases \(=\) number of diagonals in \(20\) sided polygon. \(=\,^{20}{C_2}\, - \,20\, = 170\)
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