Ex 6. Picture a parabolic arch (i. e., and upside-down parabola). It stands 40 feet tall at the center, and is 20 feet wide
at the bottom. With at least two decimal places of accuracy, find the
width of this arch at a point 6 feet up from the ground. (Tip: to avoid round-off error, you will
NOT want to round anything off until you have arrived at your final answer.)