` cos 20^(@) + cos 100^(@) +cos140^(@)` किसके तुल्य है ?

cos 20^(@) + cos 100^(@) + cos 140^(@) =

cos 20^(@) + cos 100^(@) + cos 140^(@) = 0

cos20^(@)+cos100^(@)+cos140^(@)=

cos 20^(@) cos 40^(@) cos 80^(@)=

1 + cos 10^(@) + cos 20^(@) + cos30^(@) =

cos20 ^ (@) cos40 ^ (@) cos80 ^ (@) =

The value of cos 20^(@) + cos 100^(@) + cos 140^(@) is equal to a) (1)/(2) b) (1)/(sqrt(3)) c) sqrt(3) d)0

8 cos^(3) 20^(@) -6 cos 20^(@) =

cos20^(@)cos40^(@)cos60^(@)cos80^(@)=