Chapter 17, Problem 17.12E

(Enhancing Class Rectangle) Create a more sophisticated Rectangle class than the one you created in Exercise 17.11. This class stores only the Cartesian coordinates of the four corners of the rectangle. The constructor calls a set function that accepts four sets of coordinates and verifies that each of these is in the first quadrant with no single x- or y-coordinate larger than 20.0. The set function also verifies that the supplied coordinates do, in fact, specify a rectangle. Provide member functions that calculate the length, width, perimeter and area. The length is the larger of the two dimensions. Include a predicate function square that determines whether the rectangle is a square.