Let $f(x)=\cos 5 x+A \cos 4 x+B \cos 3 x$ $+C \cos 2 x+D \cos x+E$, and
$T=f(0)-f\left(\frac{\pi}{5}\right)+f\left(\frac{2 \pi}{5}\right)-f\left(\frac{3 \pi}{5}\right)+\ldots+f\left(\frac{8 \pi}{5}\right)-f\left(\frac{9 \pi}{5}\right) \text {. }$Then, $T$
depends on $A, B, C, D, E$
depends on $A, C, E$, but independent of $B$ and $D$
depends on $B, D$, but independent of $A, C, E$
is independent of $A, B, C, D, E$
If $2\sin \theta + \tan \theta = 0$, then the general values of $\theta $ are
If $\tan (\pi \cos \theta ) = \cot (\pi \sin \theta ),$ then the value of $\cos \left( {\theta - \frac{\pi }{4}} \right) =$
The general solution of the trigonometric equation $tan\, x + tan \,2x + tan\, 3x = tan \,x · tan\, 2x · tan \,3x$ is
The equation $3{\sin ^2}x + 10\cos x - 6 = 0$ is satisfied, if
Number of solutions to the system of equations $sin \frac{x+y}{2}=0$ and $|x| + |y| = 1$