Simplify sinx cotx cosx

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

Now substitute cos(x)/sin(x) into the expression, in place of cot(x)

So now:

sin(x) cot(x) cos(x) = sin(x) cos(x) (cos(x)/sin(x) )

sin(x) cos(x) cos(x)/sin(x)

The two sin(x) cancel, leaving you with cos(x) cos(x)

Which is the same as cos2(x)

So:

sin(x) cot(x) cos(x) = cos2(x) ===