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

find the value of cos^-1cos((7pi)/3)

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

One of the value of ("cos"(pi)/(6) +i "sin"(pi)/(6))^((1)/(2)) + ("cos"(pi)/(6)- i "sin"(pi)/(6))^((11)/(2)) is

Find the value of the following: 2sin^2(pi/6)+cosec^2((7pi)/3)cos((2pi)/3)

Prove that (1+"cos"(pi)/(8))(1+"cos"(3pi)/(8))(1+"cos"(5pi)/(8))(1+"cos"(7pi)/(8))=(1)/(8) .

Prove that cos ^(4) (pi)/(8)+cos ^(4) (3 pi)/(8)+cos ^(4) (5 pi)/(8)+cos ^(4) (7 pi)/(8)=(3)/(2)

cos (2pi-x) =

The value of [ cos ""(pi)/(8) + isin ""(pi)/(8) ]^(4) is

Evaluate cos^2(pi/8)+cos^2((3pi)/8)+cos^2((5pi)/8)+cos^2((7pi)/8)=2