`cos2 0^(@)+cos4 0^(@)+cos6 0^@............+cos16 0^@+cos18 0^(@`

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

cos4 0^(@)+cos2 0^(@))=3(cos1 0^(@)+sin2 0^(@)) 40 CUSOUcos 40^@ + cos 20O 4(cos310^@ + sin320^@) = 3(cos 10^@ + sin20^@)N3.1 = 4

cos80 ^ (0) + cos40 ^ (@) - cos20 ^ (@) = 0

Prove that cos306^(@) + cos234^(@) + cos162^(@) + cos18^(@) = 0

cos10^(0)cos30^(0)cos50^(@)cos70^(0)

cos1^(0)cos2^(0)...cos179^(@)

Value of (1-(cos61^0)/(cos1^0))*(1-(cos62^0)/(cos2^0))*(1-(cos63^0)/(cos3^0)) .......... *(1-(cos119^0)/(cos59^0)) (a) -1 (b) 1 (c) 2 (d) -2

cos ^ (2) (5 ^ (0)) + cos ^ (2) (10 ^ (0)) + cos ^ (2) (15 ^ (0)) + ...... + cos ^ (2 ) (360 ^ (@))

cos20^(0)cos40^(0)cos60^(0)cos80^(0) is equal to