Chapter 12: Problem 45
Describe the set of points whose distance from the \(x\) axis equals the distance from the \(y z\) -plane.
Short Answer
Expert verified
The set of points is described by the equation \( y^2 + z^2 = x^2 \), a double cone centered on the \( x \)-axis.
Step by step solution
01
Understanding the Problem
We need to find the set of points in space where each point's distance from the \( x \)-axis is equal to its distance from the \( yz \)-plane. The \( x \)-axis in 3D space can be imagined as the line where \( y = 0 \) and \( z = 0 \) for any \( x \). The \( yz \)-plane is the plane where \( x = 0 \).
02
Distance from the x-axis to a point
If a point in space is given by \((x, y, z)\), then its distance from the \( x \)-axis is the perpendicular distance, which can be found using the formula for the distance from a point to a line: \( \sqrt{y^2 + z^2} \).
03
Distance from the yz-plane to a point
Similarly, the distance from the point \((x, y, z)\) to the \( yz \)-plane is the absolute value of the \( x \)-coordinate, which is \( |x| \) because the plane is defined as \( x = 0 \).
04
Setting Up the Equation
According to the problem, the distance from the \( x \)-axis should equal the distance from the \( yz \)-plane. Therefore, we set the distances equal: \( \sqrt{y^2 + z^2} = |x| \).
05
Solving the Equation
To solve the equation \( \sqrt{y^2 + z^2} = |x| \), we square both sides to eliminate the square root: \( y^2 + z^2 = x^2 \). This represents a double cone centered around the \( x \)-axis with its vertex at the origin and opening symmetrically along the \( x \)-axis.
06
Conclusion
The set of points where the distance from the \( x \)-axis equals the distance from the \( yz \)-plane is a double cone centered on the \( x \)-axis, which extends infinitely in the positive and negative \( x \)-directions. The equation for this cone is \( y^2 + z^2 = x^2 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Distance from a Point to a Line
In 3D geometry, the distance from a point to a line is often calculated as the shortest path between a given point and a line. When dealing with a specific scenario, such as finding the distance from a point \[(x, y, z)\] to the \(x\)-axis, this becomes finding the perpendicular distance. Here, the \(x\)-axis is defined by \(y = 0\) and \(z = 0\) \ and extends infinitely along \(x\). The shortest distance to this line from any point \((x, y, z)\) can be computed using \(\sqrt{y^2 + z^2}\).
The reasoning behind this formula stems from the fact that distance in multi-dimensional space can be evaluated using the Pythagorean theorem, effectively treating the perpendicular as a hypotenuse of a right triangle.
The reasoning behind this formula stems from the fact that distance in multi-dimensional space can be evaluated using the Pythagorean theorem, effectively treating the perpendicular as a hypotenuse of a right triangle.
- The \(y\) component represents the vertical distance from the \(x\)-axis.
- Meanwhile, the \(z\) component marks the breadth from the \(x\)-axis.
- The combination of these, using \(\sqrt{y^2 + z^2}\), gives the shortest distance.
Distance from a Point to a Plane
Moving from lines to planes in 3D geometry involves a distinct yet equally elegant method of calculating distance. When finding the distance between a point and the \(yz\)-plane, we consider the defining feature that the \(yz\)-plane occurs where \(x = 0\). Thus, for any point \((x, y, z)\), this distance can be calculated simply as \(|x|\).
The efficiency of this calculation arises from recognizing that the shortest path to the plane is purely along the \(x\)-axis. By using the absolute value, \(|x|\), we emphasize that distance is always non-negative, aligning perfectly with our intuitive understanding of distance.
The efficiency of this calculation arises from recognizing that the shortest path to the plane is purely along the \(x\)-axis. By using the absolute value, \(|x|\), we emphasize that distance is always non-negative, aligning perfectly with our intuitive understanding of distance.
- The solution does not require adjustments for the \(y\) or \(z\) components because they lie within the \(yz\)-plane.
Double Cone Geometry
In our specific problem, we discovered a fascinating geometrical feature known as a double cone. This surface occurs where the distance from the \(x\)-axis equals the distance from the \(yz\)-plane, resulting in the equation \(y^2 + z^2 = x^2\).
A double cone consists of two symmetrical cone shapes that extend infinitely away from a common vertex. Its axis of symmetry is the \(x\)-axis, aligning with our observation that the cone's vertex is at the origin, \((0, 0, 0)\).
A double cone consists of two symmetrical cone shapes that extend infinitely away from a common vertex. Its axis of symmetry is the \(x\)-axis, aligning with our observation that the cone's vertex is at the origin, \((0, 0, 0)\).
- The mathematical representation \(y^2 + z^2 = x^2\) describes a cone opening symmetrically along the positive and negative directions of the \(x\)-axis.
- This structure encapsulates all points equidistant from both the \(x\)-axis and the \(yz\)-plane.
Equations of Surfaces in 3D Space
Equations in 3D space can describe various interesting surfaces. Our exercise brings out the beauty of implicit surface equations, like the double cone \(y^2 + z^2 = x^2\).
This form of equation hints at particular geometrical and spatial characteristics:
This form of equation hints at particular geometrical and spatial characteristics:
- Here, \(x^2\) signifies the axial component determining how far the shape extends along the \(x\)-axis.
- The terms \(y^2\) and \(z^2\) define the radial spread from this axis.