Find the value of `cos""(pi)/(11)+cos""(3pi)/(11)+cos""(5pi)/(11)+cos""(7pi)/(11)+cos""(9pi)/(11)`.

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

The value of cos""(pi)/(9)cos""(2pi)/(9)cos""(3pi)/(9), is

Find the value of cos^2pi/(16)+cos^2(3pi)/(16)+cos^2(5pi)/(16)+cos^2(7pi)/(16)dot

Find the value of cos""(pi)/(12)(sin""(5pi)/(12)+cos""(pi)/(4))+sin""(pi)/(12)(cos""(5pi)/(12)-sin""(pi)/(4)) .

The value of "cos"(2pi)/(15)."cos"(4pi)/(15)."cos"(8pi)/(15)."cos"(16pi)/(15) is

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

2 cos ""(pi)/(13) cos ""(9pi)/(13) + cos ""(3pi)/(13) + cos "" (5pi)/(13) = 0.

Find the value of cos(2pi)/7+cos(4pi)/7+cos(6pi)/7

Find the value of 2cos((5pi)/12) cos(pi/12) and 2sin((5pi)/12)cos(pi/12)

Find the value of cos^2. pi/16+cos^2. (3pi)/16+cos^2. (5pi)/16+cos^2. (7pi)/16 .