Question

Aramis is adjusting a satellite because he finds it is not focusing the incoming radio waves perfectly. The shape of his satellite can be modeled by (x-4)squared =3(y-3) where x and y are modeled in inches. He realizes that the static is a result of the feed antenna shifting slightly off the focus point. Where should the feed antenna be placed?
0.75 in. below the vertex
0.75 in. to the right of the vertex
0.75 in. to the left of the vertex
0.75 in. above the vertex

Answer 1

Rewrite as (x-4)^2 = 4p(y-3) so 4p = 3 ⇒ p = 3/4 = 0.75. The vertex is (4,3) and the focus is (4, 3 + 0.75), i.e. 0.75 in. above the vertex.

Answer: 0.75 in. above the vertex.