Table of contents
- 0. Review of Algebra4h 16m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 6m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 19m
- 10. Combinatorics & Probability1h 45m
8. Conic Sections
Parabolas
Problem 17
Textbook Question
In Exercises 17–30, find the standard form of the equation of each parabola satisfying the given conditions. Focus: (7, 0); Directrix: x = - 7
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<Step 1: Understand the definition of a parabola. A parabola is the set of all points that are equidistant from a fixed point called the focus and a line called the directrix.>
<Step 2: Identify the given elements. The focus is (7, 0) and the directrix is x = -7. This indicates that the parabola opens horizontally.>
<Step 3: Determine the vertex of the parabola. The vertex is the midpoint between the focus and the directrix. Calculate the midpoint of the x-coordinates of the focus and directrix: (7 + (-7))/2 = 0. Thus, the vertex is at (0, 0).>
<Step 4: Use the standard form of a parabola that opens horizontally. The standard form is (y - k)^2 = 4p(x - h), where (h, k) is the vertex. Here, (h, k) = (0, 0).>
<Step 5: Calculate the value of p. The distance from the vertex to the focus is p. Since the focus is at (7, 0) and the vertex is at (0, 0), p = 7. Substitute p into the equation to get the standard form.>
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Standard Form of a Parabola
The standard form of a parabola that opens horizontally is given by the equation (y - k)² = 4p(x - h), where (h, k) is the vertex and p is the distance from the vertex to the focus. This form allows for easy identification of the parabola's orientation and key features, such as the focus and directrix.
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Focus and Directrix
The focus of a parabola is a fixed point from which distances to points on the parabola are measured, while the directrix is a line that is perpendicular to the axis of symmetry of the parabola. The parabola is defined as the set of points equidistant from the focus and the directrix, which is crucial for determining its equation.
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Vertex of a Parabola
The vertex of a parabola is the point where it changes direction and is located midway between the focus and the directrix. For a parabola with a focus at (7, 0) and a directrix at x = -7, the vertex can be found by averaging the x-coordinates of the focus and the directrix, which is essential for writing the equation in standard form.
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