Chapter 8: Problem 69
Find an equation for each hyperbola. Vertices \((-3,0)\) and \((3,0) ;\) passing through \((6,1)\)
Short Answer
Expert verified
The hyperbola equation is \(\frac{x^2}{9} - 3y^2 = 1\).
Step by step solution
01
Identify the Standard Form of the Hyperbola
Since the vertices are located at \((-3,0)\) and \((3,0)\), the hyperbola is horizontal. The standard form of a horizontal hyperbola centered at \((h, k)\) is \(\frac{(x-h)^2}{a^2} - \frac{(y-k)^2}{b^2} = 1\). With the given vertices, the center is \((0,0)\) and \(a = 3\). Hence, the equation is \(\frac{x^2}{9} - \frac{y^2}{b^2} = 1\).
02
Use the Given Point to Find b²
Substitute the plug-in point \((6,1)\) into the equation \(\frac{x^2}{9} - \frac{y^2}{b^2} = 1\) to find \(b^2\). Thus \(\frac{6^2}{9} - \frac{1}{b^2} = 1\).
03
Solve the Equation for b²
Calculate \(\frac{36}{9} = 4\). Then the equation becomes \(4 - \frac{1}{b^2} = 1\). So, \(-\frac{1}{b^2} = 1 - 4 = -3\), which means \(b^2 = \frac{1}{3}\).
04
Write the Equation of the Hyperbola
Substituting \(b^2 = \frac{1}{3}\) into the equation gives \(\frac{x^2}{9} - \frac{y^2}{\frac{1}{3}} = 1\), which simplifies to \(\frac{x^2}{9} - 3y^2 = 1\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Standard Form of Hyperbola
Understanding the standard form of a hyperbola equation is vital to solving problems involving hyperbolas. The equation is slightly different based on whether the hyperbola is horizontal or vertical. In this problem, we are dealing with a horizontal hyperbola. The standard form for a horizontal hyperbola centered at \((h, k)\) is:\[\frac{(x-h)^2}{a^2} - \frac{(y-k)^2}{b^2} = 1\]Where:
- \((h, k)\) is the center of the hyperbola.
- \(a\) is the distance from the center to each vertex along the x-axis.
- \(b\) is the distance related to the asymptotes.
Vertices Calculation
Calculating the vertices of a hyperbola gives us important information about its size and placement. The vertices of the hyperbola are given at \((-3,0)\) and \((3,0)\). From this, we can extract the center and the value of \(a\):
- The center is the midpoint of the line segment joining the vertices. For our vertices, the midpoint can be calculated as:\[\left(\frac{-3+3}{2}, \frac{0+0}{2}\right) = (0,0)\]
- The value of \(a\) is half the distance between the vertices. The vertices are 6 units apart, so:\(a = \frac{6}{2} = 3\)
Center and Radius
In hyperbola problems, the center and radius play similar roles to those in circles, but with some differences. The center in a hyperbola is a point \((h, k)\).The radius concept is split into two distances:
- \(a\) - the distance from the center to each vertex on the x-axis for horizontal hyperbolas.
- \(b\) - changes the slope of the asymptotes and influences the shape of the hyperbola, although it is not a direct radius like in circles.
Solving Equations
Solving the hyperbola's equation involves using the known point \((6,1)\) that lies on the hyperbola to find \(b^2\). Starting with our partial equation:\[\frac{x^2}{9} - \frac{y^2}{b^2} = 1\]Replace \(x\) and \(y\) with 6 and 1 respectively:
- Calculate: \(\frac{6^2}{9} = 4\)
- The equation simplifies to:\[4 - \frac{1}{b^2} = 1\]
- Solve for \(-\frac{1}{b^2}\):\(-\frac{1}{b^2} = 1 - 4 = -3\)
- Thus, \(b^2 = \frac{1}{3}\).