Trig Stuff 3

Geometry Level 5

p = 5 5 ( n = 5 p 1 ( m = 5 n 1 ( k = 5 m 1 ( j = 5 k 1 ( i = 5 j 1 sin ( π i 11 ) sin ( π j 11 ) sin ( π k 11 ) sin ( π m 11 ) sin ( π n 11 ) sin ( π p 11 ) ) ) ) ) ) = a b \displaystyle\sum _{p=-5}^5 \left(\displaystyle\sum _{n=-5}^{p-1} \left(\displaystyle\sum _{m=-5}^{n-1} \left(\displaystyle\sum _{k=-5}^{m-1} \left(\displaystyle\sum _{j=-5}^{k-1} \left(\displaystyle\sum _{i=-5}^{j-1} \sin \left(\frac{\pi i}{11}\right) \sin \left(\frac{\pi j}{11}\right) \sin \left(\frac{\pi k}{11}\right) \sin \left(\frac{\pi m}{11}\right) \sin \left(\frac{\pi n}{11}\right) \sin \left(\frac{\pi p}{11}\right)\right)\right)\right)\right)\right) = - \frac{a}{b}

where a,b are coprime positive integers. Submit a + b a+b .


The answer is 141.

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1 solution

Hint: Vieta's formulas.

Could you elaborate?

Sumukh Bansal - 3 years, 6 months ago

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@Sumukh Bansal - See https://en.wikipedia.org/wiki/Vieta%27s formulas#Basic formulas.

Christopher Criscitiello - 3 years, 6 months ago

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