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

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

cos^(3)A+cos^(120+A)+cos^(240+A)=(3)/(4)cos3A

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

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

Prove that : cos^(3)A cos3A+sin^(3)A sin3A=cos^(3)2A

Prove that: cos^(3)A + cos^(3)((2pi)/(3)+A) + cos^(3)((4pi)/3+A) = 3/4 cos3A

Prove that cos^(3)x+cos^(3)((2pi)/3+x)+cos^(3)((2pi)/3-x)=3/4 cos 3x

Prove that cos3A=4cos^3 A-3cosA

Prove that: (i) cos A cos(60^(@)-A)cos (60^(@)+A)=(1)/(4)cos 3A (ii) "tan" A+"tan"(60^(@)+A)-"tan"(60^(@)-A)=3 tan 3A .