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.