question: public static double distanceTo ( double x1 , double y1 , double z1 , double x2 , double y2 , double z2 ) { final double a = x1 - x2 ; final double b = y1 - y2 ; final double c = z1 - z2 ; return Math . sqrt ( a * a + b * b + c * c ) ; }
target:  Computes the Euclidean length between two points.