What is 'cotx'?

cot is a short way to write 'cotangent'. This is the reciprocal of the  trigonometric function 'tangent' or tan(x).

Therefore, cot(x) can be simplified to 1/tan(x).

Using trigonometric rules, an alternative way to write 1/tan(x)  is cos(x)/sin(x).

So cot(x)  =  1/tan(x)  =  cos(x)/sin(x)