The coordinates I'm given for a cartesian plane are (1,y) and (3,2). I'm supposed to find an answer for y that gives a hypotenuse of 4.

In the book it says "We obtain two answers: (1, 2 + 2 √3) and (1, 2 − 2 √3). The reader is encouraged to think about why there are two answers."

I'm lost on how this results in negative and positive answers. I'm unfamiliar or need refreshing with this concept and don't know where to begin. I just posted this to save time. There's an image below of the graphics from the book. Any help would be appreciated.