A searchlight has a parabolic reflector that forms a "bowl", which is 12in wide from rim to rim and 8in deep. If the filament of the light bulb is located at the focus, how far from the vertex of the reflector is it?

A parabolic mirror has a depth of 12 cm at the center, and the distance across the top of the mirror is 32 cm. Find the distance from the vertex to the focus.

The main cables of a suspension bridge are 20 meters above the road at the towers and 4 meters above the road at the center. The road is 80 meters long. The main cables hang in the shape of a parabola. Find the equation of the parabola.