JEE Main 202227 Jun, Morning shiftMathematicsMediumTrigonometry118× since 2002The value of cos(2π7)+cos(4π7)+cos(6π7)\cos \left( {{{2\pi } \over 7}} \right) + \cos \left( {{{4\pi } \over 7}} \right) + \cos \left( {{{6\pi } \over 7}} \right)cos(72π)+cos(74π)+cos(76π) is equal to :AOption A. −-−1BOption B. −-−12{1 \over 2}21COption C. −-−13{1 \over 3}31DOption D. −-−14{1 \over 4}41CheckSkip · show solution
