statement-I- `cos^3alpha + cos^3(alpha+2pi/3) + cos^3(alpha+4pi/3) = ``3cosalpha cos(alpha+2pi/3)cos(alpha+4pi/3) Because` Statement-II - `if a+b+c=0 iff a^3+b^3+c^3=3abc`

statement-I- cos^(3)alpha+cos^(3)(alpha+2(pi)/(3))+cos^(3)(alpha+4(pi)/(3))=3cos alpha cos(alpha+2(pi)/(3))cos(alpha+4(pi)/(3))Because Statement-II -0hArr a^(3)+b^(3)+c^(3)=3abc if a+b+c=0hArr a^(3)+b^(3)+c^(3)=3abc

Statement 1 is True: Statement 2 is True; Statement 2 is a correct explanation for statement 1 Statement 1 is true, Statement 2 is true;2 Statement 2 not a correct explanation for statement 1. Statement 1 is true, statement 2 is false Statement 1 is false, statement 2 is true Statement I: cos^3alpha+cos^3(alpha+(2pi)/3)+(alpha+(4pi)/3)=2cosalphacos(alpha+(2pi)/3)cos(alpha+(4pi)/3) because Statement II: In a+b+c=0=>a^3+b^3+c^3=3a c a. A b. \ B c. \ C d. D

sin alpha+sin(alpha+((2pi)/3))+sin(alpha+((4pi)/3))=0

Prove that sin alpha+sin(alpha+2pi/3)+sin(alpha+4pi/3)=0

prove sin alpha+sin(alpha+(2pi)/3)+sin (alpha+(4pi)/3)=0

(cos ^(3) alpha - cos 3 alpha )/( cos alpha ) + (sin ^(3)alpha + sin 3 alpha )/( sin alpha ) = 3.

Eliminating alpha from xcos alpha = y cos(alpha +2pi/3) = zcos (alpha +4pi/3) establish that xy + yz + zx= 0

Show that 4 sin alpha.sin (alpha + pi/3) sin (alpha + 2pi/3) = sin 3alpha

(cos alpha + 2 cos 3 alpha + cos 5 alpha )/(cos 3 alpha + 2 cos 5 alpha + cos 7 alpha ) = cos 3 alpha sec 5 alpha .

(cos alpha + (cos ((2 pi) / (3) + alpha)) + cos ((4 pi) / (3) + alpha))