Question 380119
Note that the two vertices are located on the y-axis.  Thus the y coordinate of the 3rd vertex must be midway between 0 and 4, i.e., y = 2. Hence the 3rd vertex is (x,2), where x is unknown.
Now the triangle with vertices (0,0), (0,2), and (x,2) is a 30-60-90 triangle, and so must have hypotenuse 4, shortest leg 2, and middle leg {{{2sqrt(3)}}}, by property of that triangle.  The 3rd vertx is then({{{2sqrt(3)}}}, 2).
Therefore there are two possible 3rd vertices: ({{{2sqrt(3)}}}, 2), or ({{{-2sqrt(3)}}}, 2)