ChallengeMediumTelescoping & Recursion ShareTelescoping & Recursion · Medium problemWhat is the value of cosπ7+cos3π7+cos5π7\cos\dfrac{\pi}{7}+\cos\dfrac{3\pi}{7}+\cos\dfrac{5\pi}{7}cos7π+cos73π+cos75π?A000B14\tfrac1441C12\tfrac1221D72\tfrac{\sqrt7}{2}27E111Check Show answer Walk through it step by step Practice more like this Review this concept