The value of `cos ""pi/7 cos ""(2pi)/(7) cos ""(3pi)/(7)` is-

The value of cos""(pi)/(7)+cos""(2pi)/(7)cos""(3pi)/(7)+cos""(4pi)/(7)+cos""(5pi)/(7)+cos""(6pi)/(7)+cos""(7pi)/(7) is

The value of cos (pi)/(7) . cos (2 pi)/(7) . cos (4 pi)/(7) is

The value of cos (2 pi)/(7)+cos (4 pi)/(7)+cos (6 pi)/(7) is

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

cos (pi/7) cos ((2pi)/(7) ) cos ( (4pi )/(7) ) =

The value of cos""(pi)/(11)+cos""(3pi)/(11)+cos""(5pi)/(11)+cos""(7pi)/(11)+cos""(9pi)/(11), is

The value of cos""(pi)/(11)+cos""(3pi)/(11)+cos""(5pi)/(11)+cos""(7pi)/(11)+cos""(9pi)/(11), is