Chapter 11: Problem 9
Find the vertices, foci, and asymptotes of the hyperbola, and sketch its graph. \(x^{2}-y^{2}=1\)
Short Answer
Expert verified
The vertices are \((\pm 1, 0)\); foci are \((\pm \sqrt{2}, 0)\); asymptotes are \(y = \pm x\).
Step by step solution
01
Identify the Standard Form of a Hyperbola
The given equation is \(x^2 - y^2 = 1\). Compare this with the standard form of a hyperbola \(\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1\). Here, \(a^2 = 1\) and \(b^2 = 1\), hence, \(a = 1\) and \(b = 1\).
02
Determine the Center
For the equation \(\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1\), the center of the hyperbola \((h, k)\) is determined from the lack of terms \(x-h\) and \(y-k\). Here, the center is at the origin \((0, 0)\).
03
Find the Vertices
The vertices of a hyperbola \(\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1\) are at \((h \pm a, k)\). With \(a = 1\) and center \((0, 0)\), the vertices are \((\pm 1, 0)\).
04
Find the Foci
The foci of the hyperbola \(\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1\) are located at \((h \pm c, k)\) where \(c = \sqrt{a^2 + b^2}\). Calculating \(c = \sqrt{1 + 1} = \sqrt{2}\), the foci are at \((\pm \sqrt{2}, 0)\).
05
Determine the Asymptotes
For the hyperbola \(\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1\), the equations of the asymptotes are \(y = \pm \frac{b}{a}x\). With \(a = 1\) and \(b = 1\), the asymptotes are \(y = \pm x\).
06
Sketch the Hyperbola
Sketching involves plotting the center \((0, 0)\), the vertices \((\pm 1, 0)\), and the foci \((\pm \sqrt{2}, 0)\). The asymptotes, \(y = x\) and \(y = -x\), should also be drawn as diagonal lines through the origin forming a 'X'. Sketch the hyperbola approaching these asymptotes.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vertices of Hyperbola
The vertices of a hyperbola are crucial points. They provide the tips of the hyperbola's "open ends." In the standard form, \(\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1\), the vertices are positioned at \((h \pm a, k)\). Here, \(h\) and \(k\) represent the center of the hyperbola.
Given our equation \(x^2 - y^2 = 1\), which can be rewritten as \(\frac{x^2}{1} - \frac{y^2}{1} = 1\), we find that both \(a^2\) and \(b^2\) are 1. Thus, \(a = 1\) and the center is at origin \( (0, 0) \).
Given our equation \(x^2 - y^2 = 1\), which can be rewritten as \(\frac{x^2}{1} - \frac{y^2}{1} = 1\), we find that both \(a^2\) and \(b^2\) are 1. Thus, \(a = 1\) and the center is at origin \( (0, 0) \).
- This means the vertices are at \((0 \pm 1, 0)\), simplifying to \((1, 0)\) and \((-1, 0)\).
Foci of Hyperbola
The foci of a hyperbola play a similar role to the vertices, marking points inside each "branch" of the hyperbola, pulling the curve outward. For identifying the foci, you need a number \(c\) determined by the formula \(c = \sqrt{a^2 + b^2}\).
For the equation \(x^2 - y^2 = 1\), we have \(a^2 = 1\) and \(b^2 = 1\). By plugging into the formula, \(c = \sqrt{1 + 1} = \sqrt{2}\). The foci, based on the formula, are situated at \((h \pm c, k)\).
For the equation \(x^2 - y^2 = 1\), we have \(a^2 = 1\) and \(b^2 = 1\). By plugging into the formula, \(c = \sqrt{1 + 1} = \sqrt{2}\). The foci, based on the formula, are situated at \((h \pm c, k)\).
- Thus, the foci positions are \((0 \pm \sqrt{2}, 0)\), simplifying to \((\sqrt{2}, 0)\) and \((-\sqrt{2}, 0)\).
Asymptotes of Hyperbola
Asymptotes are lines that the hyperbola approaches but never actually touches. They provide a "frame" for the hyperbola, indicating the direction in which the branches of the hyperbola extend.
For a hyperbola in the form \(\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1\), the equations of the asymptotes are \(y = \pm \frac{b}{a}x\).
For a hyperbola in the form \(\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1\), the equations of the asymptotes are \(y = \pm \frac{b}{a}x\).
- Using our values, \(a = 1\) and \(b = 1\), the equations simplify to \(y = \pm x\).