Write short answers. Consider the inverse tangent function, defined by y tan xor y arctan x. Complete parts (a)-(d) (a) What is its domain? (-00,00) (Type your answer in interval notation. Simplify your answer. Type an exact answer, using x as needed. Use integers or fractions for any numbers in the expression." (b) What is its range? (00,-00) (Type your answer in interval notation, Simplify your answer. Type an exact answer, using x as needed. Use integers or fractions for any numbers in the expression.) (c) is this function increasing or decreasing? Odecreasing increasing (d) Is there any real number x for which arctan x is not defined? If so, what is it (or what are they)? O Yes (Use a comma to separate answers as needed.)