`cos2 4^(@)+cos5 5^(@)+cos12 5^(@)+cos20 4^(@)=` 1) -1 2)0 3) 1 4)2

cos5^(0)+cos24^(0)+cos175^(0)+cos204^(0)+cos300^(@)= 1) (1)/(2) 2) 13)(3)/(2)4)2

5. cos^(2)(125^(0)-x)-cos^(2)(55^(0)+x) = (1) -1 (2) 0 (3) 1 (4) 2

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

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

sin [(1) / (2) (cos ^ (- 1) 4) / (5)]

The value of (sin 1^(@) + sin 3^(@) + sin 5^(@) + sin 7^(@))/( cos 1^(@) .cos2^(@).sin4^(@)) is"________"

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

prove cos ^(-1) (4/5)+cos ^(-1) ((12)/(13))=cos ^(-1) ((33)/(65))

COS (tan ^ (-1) (3) / (4)); cos ^ (-1) (cos5 (pi) / (4))