Chapter 10: Problem 6
Describe and sketch the surface. \(y=z^{2}\)
Short Answer
Expert verified
The surface is a parabolic cylinder extending along the x-axis.
Step by step solution
01
Identify the Equation Type
The given equation is \(y = z^2\). This is a quadratic equation in the yz-plane. It represents a parabola opening in the positive y-direction because it can be written in the form \(y = ax^2 + bx + c\) where \(x\) is replaced by \(z\), and \(a = 1, b = 0, c = 0\).
02
Recognize the Symmetry and Direction
The equation \(y = z^2\) is symmetrical about the z-axis. This means that for each positive and negative value of \(z\), \(y\) is the same, forming a U-shape along the yz-plane. This symmetry indicates that the 3D surface created by revolving this shape will also be symmetrical about the z-axis, creating a parabolic cylinder.
03
Visualize the Surface in Three Dimensions
In three dimensions, the equation \(y = z^2\) describes a surface where the cross-section in the yz-plane is a parabola. Since there is no restriction on \(x\), the parabola extends along the x-axis, forming a cylindrical shape. This results in a parabolic cylinder aligned parallel to the x-axis.
04
Sketch the Parabolic Cylinder
To sketch the surface described by \(y = z^2\), draw the parabola in the yz-plane, with the vertex at the origin (0, 0), curving upwards. Extend this parabolic shape infinitely along the x-axis in both directions, maintaining the same U-shaped cross-section at every x-coordinate. This forms a parabolic cylinder along the x-axis.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Equation in 3D Geometry
A quadratic equation typically takes the form of \( y = ax^2 + bx + c \). In three-dimensional geometry, such equations are not limited to simple 2D curves. The equation \( y = z^2 \) is a specific type of quadratic equation, representing a parabola. In this case, \( a = 1 \), \( b = 0 \), and \( c = 0 \). It opens upwards, indicating that as \( z \) becomes larger or smaller, \( y \) correspondingly increases.
- The parabola is centered at the origin (0, 0) in the yz-plane, making it a simple U-shape.
- Given its quadratic nature, this equation generates a continuous and smooth curve.
- One key characteristic of quadratic equations in 3D is their versatility in shaping various geometric surfaces.
Symmetry and Its Role in Parabolic Surfaces
Symmetry is a fundamental characteristic of many geometric forms. In the equation \( y = z^2 \), symmetry about the z-axis is evident. This means that the parabola created is perfectly mirrored on either side of the z-axis. Each positive value of \( z \) has a corresponding negative value, maintaining equal values of \( y \).
Such symmetry results in significant implications for the 3D surface.
Such symmetry results in significant implications for the 3D surface.
- When considering the whole surface in three dimensions, this symmetry means the geometric formation will appear identical from multiple perspectives perpendicular to the x-axis.
- This bilateral symmetry provides easy visualization and consistency in mathematical representation.
- Understanding this symmetrical nature aids in sketching and conceptualizing 3D shapes efficiently.
Visualizing the Parabolic Cylinder in Three Dimensions
In three-dimensional space, a parabolic equation like \( y = z^2 \) translates into a parabolic cylinder. Though 'cylinder' might evoke thoughts of smooth, rounded tubes, a parabolic cylinder is fundamentally different.
The surface formed extends the familiar 2D parabolic curve along a new dimension.
The surface formed extends the familiar 2D parabolic curve along a new dimension.
- This shape features a consistent cross-section, which remains a parabola as you "move" along the x-axis.
- The absence of an \( x \) variable in the equation allows free expansion along this axis, creating the cylindrical appearance.
- Visualizing this involves considering a parabola standing in the yz-plane, then imagining it running infinitely parallel to the x-axis.