cos(pi)/(7)cos(2 pi)/(7)cos(4 pi)/(7)=-(1)/(8)

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

prove that cos2(pi)/(7)+cos4(pi)/(7)+cos6(pi)/(7)=-(1)/(2)

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

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

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

Show that cos(pi/7)cos((2pi)/7)cos((3pi)/7)=1/8

Prove that : cos(pi/7)cos((2pi)/7) cos((3pi)/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

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