Vertex coordinates transverse coordinates -b/2a , (4ac-b^2)/4a D (1,-4)
Existence, P (0,0) A short note: over the D do the perpendicular line of the axis, so as to introduce the foot of the pendant E. Then triangle BOC and triangle CED is isosceles right triangle
by the image axis of symmetry X = 1 D (1,-4) and OC = OB = 3 angle BCD right angle
has the collinear theorem respectively, the sides are: BC = 3 root 2 CD = root 2 BD = 2 root 5 PC = 3PA = 1 AC = root 10
three pairs of strain Ratio is: root number 2 Therefore, it exists.