`cos(2 pi)/(7)*cos(4 pi)/(7)*cos(8 pi)/(7)`=`(1)/(8)`

3.Prove that (i) "cos((2pi)/7)*cos((4pi)/7)*cos((8pi)/7)=1/8

Prove that cos(2pi)/(15)cos(4pi)/(15)cos(8pi)/(15)cos(14pi)/(15)=1/(16)

Prove that: cos(pi/5)cos((2pi)/5)cos((4pi)/5)cos((8pi)/5)=(-1)/16

If the value of cos((2pi)/7) + cos((4pi)/7)+cos((6pi)/7)+cos((7pi)/7)=-l/2 Find the value of l

Prove that cos ((2pi)/7)+ cos ((4pi)/7) + cos ((6pi)/7) = - 1/2

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

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 1 (b) -1 (c) 0 (d) none of these

Show that 16cos((2pi)/(15))cos((4pi)/(15))cos((8pi)/(15))cos((16pi)/(15))=1

cos""(2pi)/(15)cos""(4pi)/(15)cos""(8pi)/(15)cos""(16pi)/(15)=(1)/(16)

Prove that cos((2pi)/(15))cos((4pi)/(15))cos((8pi)/(15))cos((14pi)/(15))=1/(16)