Broadcasters use a parabolic microphone on football sidelines to pick up field audio for broadcasting purposes. A certain parabolic microphone has a reflector dish with a diameter of 14 inches and a depth of 4 inches. If the receiver of the microphone is located at the focus of the reflector​ dish, how far from the vertex should the receiver be​ positioned?

Respuesta :

Given:
diameter = 14 inches
depth = 4 inches

radius = 14 / 2 = 7 inches

(x,y) → (7,4) 

y = 1/4c * x²
4 = 1/4c * 7²
4 * 4c = 49
16c = 49
c = 49/16
c = 3.0625 inches

The receiver should be positioned 3.0625 inches from the vertex.