1. Distance formula:

public static double distance(double x1, double y1, double x2, double y2) { return Math.sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1)); }

Note that the keyword `static` is not essential for this problem, althugh we will learn why it makes sense later in the semester.

Refer to the Cow problem from the beginning of the semester for #2.