The expression sin(3x)cos(x)+cos(3x)sin(x)\frac{\sin(3x)}{\cos(x)} + \frac{\cos(3x)}{\sin(x)}cos(x)sin(3x)+sin(x)cos(3x) is equivalent to:
2csc(2x)2\csc(2x)2csc(2x)
4cot(2x)4\cot(2x)4cot(2x)
2sec(2x)2\sec(2x)2sec(2x)
2tan(2x)2\tan(2x)2tan(2x)