`cos^2(3pi/5)*cos^2(4pi/5)`

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

The value of cos(pi)/(5)cos.2(pi)/(5)cos4(pi)/(5)cos8(pi)/(5)=

cos^(2)((3 pi)/(5))+cos^(2)((4 pi)/(5))=

What is sin^(2)(3pi)+cos^(2)(4pi)+tan^(2)(5pi) equal to ?

What is sin^2(3pi)+cos^2(4pi)+tan^2(5pi) 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 ?

Prove that: (cos pi)/(5)(cos(2 pi))/(5)(cos(4 pi))/(5)(cos(8 pi))/(5)=(-1)/(6)

cos^(2)""(pi)/(16)+cos^(2)""(3pi)/(16)+cos^(2)""(5pi)/(16)+cos^(2)""(7pi)/(16)=?