If `sin4x+sin3xcos7x=cos3x` then which of the following can be true?

If x=cos^(-1)(cos4)" and "y=sin^(-1)(sin3) , then which of the following conditions is true ?

Let quad cos x+cos2x+cos3x+cos4x+cos5x+cos6x+cos7xy=(cos x+cos2x+cos3x+cos4x+cos5x+cos6x+cos7x)/(sin x+sin2x+sin3x+sin4x+sin5x+sin6x+sin7x), then which of the following holds good?

If sin x+cos x=1+sin x.cos x then x=

sin^(3)xcos^(3)x

(sin 7x + sin 3x )/(cos 7x + cos 3x ) = tan 5x.

If sin^3xcos3x+cos^3xsin3x=3/8, then the value of 8sin4x is__

If sin^3xcos3x+cos^3xsin3x=3/8, then the value of 8sin4x is__

If sin^3xcos3x+cos^3xsin3x=3/8, then the value of 8sin4x is__

sin4x=4sin x cos^(3)x-4cos x sin^(3)x

Prove : (sin 7x +sin 3x)/(cos 7x+cos 3x) = tan 5x