The reflecting dish of a parabolic microphone has a cross-section in the shape of a parabola. the microphone itself is placed on the focus of the parabola. if the parabola is 24 inches wide and 9 inches deep, how far from the vertex should the microphone be placed?
1. B. ellipse
Domain: {–4 ≤ x ≤ 4}
Range: {–3 ≤ y ≤ 3}
2. B. y= x²/4
3. D. y = 1/6x²
4. D. 4 inches
5. D. x = 1/12(y – 4)2 + 2
6. B. (x – 4)² + (y – 5)² = 49
7. (x + 7)² + (y + 2)² = 25
8.D. (x + 3)² + (y + 2)² = 9
9. B. Center at (5,-3); radius: 5
10. D. x²/23 + y²/144 = 1
11. A. (0, ±6)
12. C. 10 feet
13. A. (6,0) and (-6,0)
14. A. (0, ± 5)
let the parabola have the form y^2 = 4px, where (p,0) is the focus
the point (9,12) would lie on this curve, so
144 = 4p(9)
4p = 144/9 = 16
p = 4 , focus is (4,0)
So the microphone should be placed 4 inches from the vertex.
dont trust only letter answers. if you see a written out answer that has the same question number on your test, and matches an available answer to that question, it's the correct one. for answers you dont get from here, just look up the questions individually
please be careful with only letter answers! they give different equations during quizzes!!
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Just be careful because for math they are different in most test
So are these the right answers or no
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