Hello,Originally Posted by freswood
if the vertex of the parabola has the coordinates (z, v) then the equation of the parabola, which you should use, is:
You've got 3 points, which belong to the parabola:
Put in the coordinates of these points into the equation and you'll get:
Solve the 1rst equation for a:
and put it into the 2nd equation. You'll get:
Solve for z. The results are: z=3 or z=15
I've attached a graph to demonstrate these results.