Well, function is already written in "function notation" though not explicitly which I assume is "function notation".
Explicit notation for this function is:

Hope this helps.
Answer:
x=3
Step-by-step explanation:
C is the answer I think if it’s not I’m sorry
Answer:
see below
Step-by-step explanation:
sin x cos x = cot x
We need to show a counter example
Let's use 30 degrees
sin 30 cos 30 = cot 30
1/2 * sqrt(3) /2 = sqrt(3)
sqrt(3)/4 = sqrt(3)
not true