Chapter 10: Problem 116
For the following exercises, given information about the graph of the hyperbola, find its equation. Center: \((0,0) ;\) vertex: \((0,-13) ;\) one focus: \((0, \sqrt{313})\)
Short Answer
Expert verified
The equation of the hyperbola is \( \frac{y^2}{169} - \frac{x^2}{144} = 1 \).
Step by step solution
01
Identify Hyperbola Type
Since the vertex and focus are both aligned along the y-axis, the hyperbola is vertical. The general equation for a vertical hyperbola centered at the origin is \( \frac{y^2}{a^2} - \frac{x^2}{b^2} = 1 \).
02
Find \(a^2\) using the Vertex
The vertex form of a vertical hyperbola is \((0, \pm a)\). Given the vertex \((0, -13)\), we have \(a = 13\). Therefore, \(a^2 = 13^2 = 169\).
03
Calculate \(c^2\) using the Focus
The focus form for a vertical hyperbola is \((0, \pm c)\). Given a focus at \((0, \sqrt{313})\), we have \(c = \sqrt{313}\), so \(c^2 = 313\).
04
Find \(b^2\) using the Hyperbola Relationship
For hyperbolas, it is true that \(c^2 = a^2 + b^2\). Substituting the known values, \(313 = 169 + b^2\). Solving for \(b^2\), we find \(b^2 = 313 - 169 = 144\).
05
Write the Equation of the Hyperbola
Substitute \(a^2\) and \(b^2\) into the standard vertical hyperbola equation: \( \frac{y^2}{169} - \frac{x^2}{144} = 1 \). Therefore, the equation of the hyperbola is \( \frac{y^2}{169} - \frac{x^2}{144} = 1 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Vertical Hyperbolas
A hyperbola is a type of conic section that consists of two disconnected curves, or "branches". In the case of a vertical hyperbola, the branches open upwards and downwards, along the y-axis. The orientation is crucial: it tells us how the branches are aligned. For a vertical hyperbola, the standard equation is \( \frac{y^2}{a^2} - \frac{x^2}{b^2} = 1 \). The key features are the following:
- The center of the hyperbola is a fixed point, typically denoted as \((h, k)\). In simpler cases like this one, it is at the origin \((0,0)\).
- The vertices are directly above and below the center if the hyperbola is vertical.
- The terms \(a\) and \(b\) represent distances from the center, influencing the shape and spread of the hyperbola.
Locating the Focus of a Hyperbola
The foci, or focus points, of a hyperbola are significant because they determine the curvature of its branches. For a vertical hyperbola, the foci also lie along the y-axis. Here's how it works:
- The coordinates of the foci are \((h, k \pm c)\) if the center is at \((h, k)\). Typically, in a simple hyperbola centered at the origin, these are just \((0, \pm c)\).
- The distance \(c\) is calculated based on the distances \(a\) and \(b\), where \(c^2 = a^2 + b^2\).
- This means that the foci are located a distance \(c\) from the center along the axis of the hyperbola (y-axis in this case).
Defining the Vertex of a Hyperbola
The vertex represents the "turning point" where each branch of the hyperbola changes direction. For a vertical hyperbola, this understanding is especially handy:
- The vertices of a vertical hyperbola are situated at \((h, k \pm a)\). Here, with a center at \((0,0)\), they are \((0, \pm a)\).
- The distance \(a\) is the distance from the center to a vertex along the line of symmetry (again, the y-axis).
- The given vertex \((0, -13)\) signifies that \(a = 13\), hence providing valuable information for formulating the hyperbola's equation.
Understanding the Hyperbola Standard Form
The standard form of a hyperbola's equation provides a concise representation of its important features. For a vertical hyperbola, it's written as \( \frac{y^2}{a^2} - \frac{x^2}{b^2} = 1 \). Here's a breakdown:
- The numerator \(y^2\) tells us the branches are opening along the y-axis, confirming the hyperbola's vertical orientation.
- \(a^2\) and \(b^2\) are pivotal as they denote squared distances from the center to the vertices and co-vertices, respectively. Calculating these involves understanding the vertex and focus positions.
- The equation \(c^2 = a^2 + b^2\) links all these components, allowing us to calculate \(b^2\) if we know \(a^2\) and \(c^2\).