2. An arch is in the form of a parabola with its axis vertical. The arch is 10 m high and 5 m wide at the base. How wide is it 2 m from the vertex of the parabola?
Since the Axis of the parabola is vertical, Let the equation of the parabola be,
it can be seen that this curve will pass through the point (5/2, 10) if we assume origin at the bottom end of the parabolic arch.
Hence, the equation of the parabola is
Now, when y = 2 the value of x will be
Hence the width of the arch at this height is