That is if u used the distance....................above negative one.................to i ........................I just used the 3rd d to be the imaginary axis.......making it perpendicular to the other two........but if u used the z axis.......the 3rd d axis as i...........u would get the square root of 8.....which is 2 times the square root of 2........

So there are two ways of looking at it...............using the height as i................I get the 2 times the square root of 2..........the square root of 8, simplified...........why?  i squared is negative one......added to 9..................3 squared.....................9 + - 1 = 8...................the hypotenuse is the square root of that.....................