`cos (pi/11) cos(2 pi/11) cos(3 pi/11) cos(4 pi/11) cos(5pi/11)`

let x_(1)=cos((pi)/(11))cos((2 pi)/(11))cos((3 pi)/(11))cos((4 pi)/(11))cos((5 pi)/(11)) and x_(2)=cos((pi)/(11))+cos(2(pi)/(11))+cos(3(pi)/(11))+cos(4(pi)/(11))+cos(5(pi)/(11)) then show that x_(1).x_(2)=(1)/(64)(cos ec((pi)/(22))-1)

The value of 2(cos pi/11 + cos(3pi)/11 + cos(5pi)/11 + cos(7pi)/11 + cos(9pi)/11) is……….

cos(pi)/(11)+cos(3 pi)/(11)+cos(5 pi)/(11)+cos(7 pi)/(11)+cos(9 pi)/(11)=(1)/(2)

cos ((pi) / (11)) cos (2 (pi) / (11)) cos (3 (pi) / (11)) cos (4 (pi) / (11)) cos (5 (pi) / (11))

If P=cos(pi)/(20)*cos(3 pi)/(20)*cos(7 pi)/(20)*cos(9 pi)/(20)&Q=cos(pi)/(11)*cos(2 pi)/(11)*cos(8 pi)/(11)*cos(16 pi)/(11) , then (P)/(Q) is not defined (b) 1 (c) 2 (d) None of these

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

cos((pi)/(15))cos((2 pi)/(15))cos((pi)/(5))cos((4 pi)/(15))cos((2 pi)/(5))cos((7 pi)/(15)) is equal to

If the value of "cos"pi/15"cos"(2pi)/15"cos"(3pi)/15"cos"(4pi)/15"cos"(5pi)/15"cos"(6pi)/15"cos"(7pi)/15 is (1)/(2^(k)) , then which of the following is true ?

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

cos ((pi) / (11)) cos ((2 pi) / (11)) cos ((3 pi) / (11)) ... cos ((11 pi) / (11)) =