" 1."cos x*cos2x*cos3x

Prove that 1 + cos 2x + cos 4x + cos 6x = 4 cos x *cos 2x *cos 3x .

lim_(x->0) (1-cos x cos 2x cos 3x)/ (sin^2 2x) is equal to a) 3/4 b) 7/4 c) 7/2 d) -3/4

lim_(x->0) (1-cos x cos 2x cos 3x)/ (sin^2 2x) is equal to a) 3/4 b) 7/4 c) 7/2 d) -3/4

Prove that 1 + cos 2x + cos 4x + cos 6x = 4 cos x cos 2x cos 3x

1+ cos 2x + cos 4 x+ cos 6x- 4 cos x cos 2x cos 3x =

If cos ecx=(2)/(sqrt(3)) and cot x=-(1)/(sqrt(3)) for xin[0,2 pi] then cos x+cos2x+cos3x+...+cos100x is

Solve cos x cos2x cos3x=(1)/(4)

If cos ecx=(2)/(sqrt(3)) and cot x=(-1)/(sqrt(3))x in[0,2 pi], then the value of cos x+cos2x+cos3x is equal to