Question

The 45-degree line: what is the special characteristic of a 45-degree line and what is its slope equal to?

Answer 1

The special feature is:
 For each value of the domain of the function, the value of the range of the function is the same.
 That is to say,
 Domain = Range
 The slope of the line is equal to 1 since:
 Tan (45) = 1
 Answer:
 Domain = Range
 Slope = 1