Simplify the expression cos(3x)+cos(x)sin(3x)−sin(x)\frac{\cos(3x) + \cos(x)}{\sin(3x) - \sin(x)}sin(3x)−sin(x)cos(3x)+cos(x).
\tan(x)
\cot(x)
1/\tan(2x)
\cot(2x)