. . Inverse cotangent function The cotangent function is not one-to-one in its entire domain \ : ∈ { } . However, cot : π ) →−∞∞ ) is bijective with the restricted domain , π ) .
So, we can define the inverse cotangent function with −∞∞ as its domain and , π ) as its range. Definition . The inverse cotangent function cot : −∞∞ ) → ( π is defined by cot ( ) x y if and only if cot y and y ∈ ( , π .