" (iv) "cos20^(@)+cos100^(@)+cos140^(@)=0

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

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

Prove that: cos20^(@)+cos100^(@)+cos140^(@)=-0

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

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

Find the value of cos20^(@)+cos100^(@)+cos140^(@):

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

The value of cos20^(@)cos100^(@)+cos100^(@)cos140^(@)-cos140^(@)cos200^(@) is equal to