In trigonometric function: cotθ = cos θ/sin θ, cotθ = 1/tan θ.
Y=cot x x cannot be equal to kπ.
Modern definition:
Put an angle into a rectangular coordinate system
Make the starting edge of the angle coincide with the non-negative semi-axis of the X axis.
Find a point A(x, y) on the terminal edge of the corner.
Through a perpendicular to the x axis.
Then r = (x 2+y 2) (1/2)
cot=x/y
There is no maximum or minimum cotangent.