The value of `cospi/7+cos(2pi)/7+cos(3pi)/7+cos(4pi)/7+cos(5pi)/7+cos(6pi)/7+cos(7pi)/7` is 1 (b) `-1` (c) 0 (d) none of these

cos.(2pi)/(7)+cos.(4pi)/(7)+cos.(6pi)/(7)

the value of (cos pi)/(7)cos(2(pi)/(7))cos(3(pi)/(7)) is

The value of cos((pi)/(7))+cos((2 pi)/(7))+cos((3 pi)/(7))+cos((4 pi)/(7))+cos((5 pi)/(7))+cos((6 pi)/(7))+cos((7 pi)/(7)) is 1(b)-1(c)0(d) none of these

Find the value of cos(2 pi)/(7)+cos(4 pi)/(7)+cos(6 pi)/(7)

The value of 2(cos pi/11 + cos(3pi)/11 + cos(5pi)/11 + cos(7pi)/11 + cos(9pi)/11) is……….

Prove that cos((2pi)/7) cos((4pi)/7) cos((8pi)/7) =1/8

Find the value of (cos(2 pi))/(7)(cos(4 pi))/(7)(cos(6 pi))/(7)