The value of `prod_(r=1)^(7)cos\ (pi r)/(15)` is

If alpha=pi/(15),\ then the value of prod_(r=1)^7cos ralpha is- a. 1/(128) b. 1/(128) c. 1/(64) d. 1/(32)

If alpha=(pi)/(13) then the value of prod_(r=1)^(6)cos r alpha is equal to

let z_1,z_2,z_3 and z_4 be the roots of the equation z^4 + z^3 +2=0 , then the value of prod_(r=1)^(4) (2z_r+1) is equal to :

let z_1,z_2,z_3 and z_4 be the roots of the equation z^4 + z^3 +2=0 , then the value of prod_(r=1)^(4) (2z_r+1) is equal to :

The value of prod_(k=1)^6((sin)(2pik)/(7)-(icos)(2pik)/(7)) is

The value of sum_(r=0)^(10)cos^(3)((r pi)/(3)) is

The value of Lt_(n rarr oo)prod_(r=1)^(n)((n+r)/(n))^((1)/(n)) equals

The value of cos((pi)/(15))cos((2 pi)/(15))cos((4 pi)/(15))cos((8 pi)/(15))=