Arithmetic Ability
Permutations and Combinations

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Q.

A polygon has 44 diagonals, then the number of its sides are ?

View Answer

Correct choice: C

Explanation:

Let the number of sides be n. The number of diagonals is given by nC2 - n Therefore, nC2 - n = 44, n>0 nC2 - n = 44 n2 - 3n - 88 = 0 n2 -11n + 8n - 88 = 0 n(n - 11) + 8(n - 11) = 0 n = -8 or n = 11. As n>0, n will not be -8. Therefore, n=11.
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