the reflector of a flashlight is in the shape of parabolic surface. The the reflections of all rays from the light bulb to any point on the parabolic surface will be all parallel to each other. The casting has a diameter of 16 cm and a depth of 8 cm. Find the the focus to determine how far the light bulb should be placed from the vertex.the light bulb should be placed ? centimeters (s) from the vertex