cos^(2)a+cos^(2)(a+120^(@))+cos^(2)(a-120^(@))=(3)/(2)

cos^(2)alpha+cos^(2)(alpha+120^(@))+cos^(2)(alpha-120^(@))=(3)/(2)

cos^(2) A + cos^(2) ( 120^(@) + A)+ cos^(2) (120^(@) - A )=

Prove that cos^(3)A+cos^(3)(120^(@)+A)+cos^(3)(240^(0)+A)=(3)/(4)cos3A

cos120^(@)=

Prove that : cos^(2)A+cos^(2)(A+pi/3)+cos^(2)(A-pi/3) =1/2[2cos^(2)A+2cos^(2)(A+60^(@))+2cos^(2)(A-60^(@))] =1/2[1+cos2A+1+cos(2A+120^(@))+1+cos(2A-120^(@))] 1/2[3+cos2A+cos(2A+120^(@))+cos(2A-120^(@))] 1/2[3+cos2A+2cos(2A+120^(@)+2A-120^(@))/(2).cos(2A+120^(@)-2A+120^(@))/(2)] =1/2[3+cos2A+2cos2Acos120^(@)] =1/2[3cos2A+2cos2Acos(90^(@)+30^(@))] =1/2[3+cos2A-2.cos2A.(1/2)] =1/2(3+cos2A-cos2A) =3/2 = RHS Hence Proved.

cos^(2)alpha+cos^(2)(alpha+120^(@))+cos^(2)(alpha-120^(@))=?

Prove the following: cos^2x+cos^2(x+120^@)+cos^2(x-120^@)=3/2

cos ^(2) alpha + cos ^(2) (alpha + 120^(@)) + cos ^(2) (alpha - 120^(@)) is equal to

cos ^(2) alpha + cos ^(2) (alpha + 120^(@)) + cos ^(2) (alpha - 120^(@)) is equal to