Chapter 10: Problem 6
Consider the hyperbola \(x^{2}-y^{2}=1\) in the plane. If this hyperbola is rotated about the \(y\) -axis, what quadric surface is formed?
Short Answer
Expert verified
The surface formed is a hyperboloid of revolution.
Step by step solution
01
Identify the given equation
The given hyperbola is described by the equation \(x^2 - y^2 = 1\). This defines a hyperbola centered at the origin in the \(xy\)-plane.
02
Determine the axis of rotation
We are tasked to rotate the hyperbola about the \(y\)-axis. This means every point on the hyperbola will trace a circular path around the \(y\)-axis, generating a surface in three-dimensional space.
03
Establish the generated surface
When a curve defined by \(x^2 - y^2 = 1\) is rotated around the \(y\)-axis, a three-dimensional surface is formed. Specifically, each point \((x, y)\) on the hyperbola generates a circle of radius \(|x|\) when rotated around the \(y\)-axis. This leads to the generation of a hyperboloid of revolution.
04
Verify the type of hyperboloid
The original equation \(x^2 - y^2 = 1\) does not involve the \(z\)-axis. However, upon rotation, for each \(z\) corresponding to \(x^2 = 1 + y^2 + z^2\), we recognize the structure of a two-sheeted hyperboloid. As \(y\) or \(z\) increases, the \(x\) dimension adjusts, suggesting a hyperboloid of two sheets.
05
Confirm the resulting equation
To formally describe the resulting surface, replace \(x^2\) with the expression for a circle radius in the \(xz\)-plane by adding \(z^2\) as it accommodates the rotational aspects. Thus, the equation becomes \(x^2 = y^2 + z^2 + 1\), which is a hyperboloid of one sheet.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Rotation of Curves
When curves are rotated in three-dimensional space, they generate surfaces, creating a fascinating geometric phenomenon. Rotating a two-dimensional curve about an axis transforms it into a three-dimensional surface. In the case of the hyperbola, which is defined by the equation \( x^2 - y^2 = 1 \), rotating it around the \( y \)-axis causes every point on the curve to trace out a circular path.
- This circular path forms a surface in three dimensions.
- Each point on the hyperbola expands into a circle, which is integrated into the overall structure of the surface.
- Such rotations are a prelude to understanding complex geometries and forms in higher-dimensional spaces.
Hyperbola
A hyperbola is a distinct type of curve defined by its equation, such as \( x^2 - y^2 = 1 \). Hyperbolas take a characteristic shape that resembles two opposite-facing arcs. Let's delve into some of its unique properties:
- Hyperbolas consist of two disconnected curves called branches.
- It is symmetrical about its principal axes, which in this standard equation are the \( x \)-axis and \( y \)-axis.
- The equation defines a pair of intersecting lines at larger values, known as asymptotes, which the branches approach but never touch.
Three-Dimensional Surfaces
Three-dimensional surfaces are forms that extend through space, having width, depth, and height. They're generated from simple curves by rotations or other transformations. When the two-dimensional hyperbola \( x^2 - y^2 = 1 \) is rotated about the \( y \)-axis, it expands into a surface known as a hyperboloid. Key points about these surfaces include:
- They are critical in fields like architecture, where their aesthetic and structural properties are utilized.
- Unlike flat surfaces, they can support complex interactions with light, shadow, and texture.
- Hyperboloids of one sheet, generated in this case, show up regularly in industrial designs such as cooling towers.
Quadric Surfaces
The term 'quadric surfaces' refers to a group of surfaces in three-dimensional space defined by second-degree algebraic equations. These surfaces, including spheres, ellipsoids, and hyperboloids, have unique characteristics based on their equations. For instance, our rotated hyperbola becomes a hyperboloid of one sheet when integrated into the equation \( x^2 = y^2 + z^2 + 1 \). Here's what makes quadric surfaces interesting:
- They display symmetry, which aids in their aesthetic appeal and structural capabilities.
- Quadric surfaces are employed in computer graphics for rendering realistic scenes due to their complex shapes yet computational simplicity.
- They provide insights into physical phenomena, such as gravitational potential surfaces.