cos(pi)/(7)cos(2 pi)/(7)*cos(3 pi)/(7)" equals to "

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

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

The value of cos(pi)/(8)cos(3 pi)/(8)cos(5 pi)/(8)cos(7 pi)/(8) is equal to

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

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 (4 pi)/(7) is

1+cos((2 pi)/(7))+cos((4 pi)/(7))+cos((6 pi)/(7)) is equal to (i)-(1)/(2)(ii)0( iii) (1)/(2)(iv)(3)/(2)

Prove that :(cos pi)/(7)(cos(2 pi))/(7)(cos(3 pi))/(7)(cos(4 pi))/(7)=(1)/(8)

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