Whisper dishes are parabolic dishes that reflect sound back and forth to each other. The best place to receive sound is at the focus of the dish. The waterpark owners want to include a set of whisper dishes at the water park that face each other across one of the pools. What is the equation of the parabola of the dish if the best place to stand to hear someone whisper into the other dish is 2 feet from the vertex of the dish?