cos theta+cos(240^(@)+theta)+cos(240^(@)-theta)=

Show that cos theta+cos(120^(@)+theta)+cos(240^(@)+theta)=0

Prove that cos theta + cos (120^(@) + theta) + cos ( 120^(@)-theta) =0. Hence deduce that cos ^(3) theta + cos ^(3) ( 120^(@) + theta ) + cos^3( 120^(@)-theta) = 3/4 cos 3 theta.

Statement I: If x cos theta=y cos(120^(@)+theta)=z cos(theta+240^(@)) then xy+yz+zx=1 Statement II: cos alpha+cos(120^(@)+alpha)+cos(120^(@)alpha)=0 Which of the above statements is correct

cos A + cos (240^(@) +A)+ cos (240^(@)-A)=

sin ( 240^(@) + theta) + cos (330^(@) + theta ) = 0

The value of the expression cos^3theta+cos^3(120+theta)+cos^3(240+theta) is;

I : If x cos theta = y cos (120^@ + theta ) = z cos ( theta + 240^(@)) then xy+ yz+ zx=1 II : cos alpha + cos (120^(@) + alpha ) + cos (120^@ - alpha ) =0

2 cos theta - cos 3 theta - cos 5 theta - 16 cos^(3) theta sin^(2) theta =