Find the value of `cos(pi/6)`

Find the value of cos((2pi)/5).cos(pi/5)

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

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

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

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

Find the value of cos^(4)((pi)/(8))

Find the value of 1 cos(29pi//3)

Find the value of cos((19pi)/3)

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

If cos A=4/(5), cosB=12/13 and (3pi)/2 < A, B < 2pi then find the value of cos(A+B)