`cos1 2^(@)+cos6 0^(@)+cos8 4^(@)=cos2 4^(@)+cos4 8^(@)`

Prove that cos 2 0^(@)cos4 0^(@)cos6 0^(@)cos8 0^(@)=1/16

(sin2^(@)+sin4^(@)+sin6^(@)+sin8^(@))/(cos1^(@)*cos2^(@)*cos5^(@))=

If sinA+sin^(2)A=1 , then find the value of cos^(12)A+3cos^(10)A+3cos^(8)A+cos^(6)A+cos^(4)A+cos^(2)A .

8.sin(x/8). cos (x/2).cos (x/4).cos (x/8) =

cos4A=1-8cos^(2)A+8cos^(4)A

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

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

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

lim_ (x rarr0) (8) / (x ^ (8)) (1- (cos (x ^ (2))) / (2) - (cos (x ^ (2))) / (4) + ( cos (x ^ (2))) / (2) (cos (x ^ (2))) / (4))

If sin x+sin^(2)x+sin^(3)x=1 then cos^(6)x-4cos^(4)x+8 cos^(2)x=