`cos^3 1 0^(@)+cos^3 11 0^(@)+cos^3 13 0^(@)=`

Prove that cos 80^(@) - cos 40^(@) + sqrt3 cos 70^(@) = 0

cos 1^(@) ."" cos 2^(@) ."" cos 3^(@) "…." cos 179 ^(@)= ................. A) 0 B) 1 C) -1/2 D) -1

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 1^(@) + cos2^(@) + cos 3^(@) + ….+cos 180^(@) is equal to............. (A) 0 (B) 1 (C) -1 (D) 2

The value of cos^(2)10^(0)-cos10^(0)cos50^(@)+cos^(2)50^(@) is equal to (4)/(3)(b)(1)/(3)(c)(3)/(4)(d)3

cos A + cos (240^(@) +A)+ cos (240^(@)-A)= ............... A) cos A B) 0 C) sqrt3 sin A D) sqrt3 cos A