1. Tardigrade
  2. Question
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  4. Let the exact value of expression E= cos (π/7)+ cos 2 (π/7)-2 cos 3 (π/7) is a rational number in the form p / q. where p and q are natural numbers and co-prime, then ( p + q )=

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Q. Let the exact value of expression $E=\cos \frac{\pi}{7}+\cos ^2 \frac{\pi}{7}-2 \cos ^3 \frac{\pi}{7}$ is a rational number in the form $p / q$. where $p$ and $q$ are natural numbers and co-prime, then $( p + q )=$

JEE AdvancedJEE Advanced 2021

Solution:

Correct answer is (c) 5