Chapter 12: Problem 15
In Exercises \(1-16,\) give a geometric description of the set of points in space whose coordinates satisfy the given pairs of equations. $$y=x^{2}, \quad z=0$$
Short Answer
Expert verified
A parabola in the \(xy\)-plane, opening upwards from the origin.
Step by step solution
01
Identify the given equations
We are given two equations: \( y = x^2 \) and \( z = 0 \). The first equation is a parabolic equation in the \(xy\)-plane and the second equation implies we are considering points on the \(xy\)-plane because \(z\) is always zero.
02
Analyze the first equation
The equation \( y = x^2 \) represents a parabola that opens upwards in the \(xy\)-plane. It describes all points \((x, y)\) such that the \(y\)-coordinate is the square of the \(x\)-coordinate.
03
Consider the second equation
The equation \( z = 0 \) means that all over space, we are considering points that lie on the \(xy\)-plane, since there is no \(z\)-component that elevates or depresses any point off this plane.
04
Combine both conditions
With \(y = x^2\) and \(z = 0\), the set of points that satisfy these equations form a parabolic shape in the \(xy\)-plane. Any point \((x, y, z)\) can be described as \((x, x^2, 0)\), which lies on the parabola in the plane with no elevation off it.
05
Geometric description
The set of points described by these equations is a parabola in the \(xy\)-plane (which resides flat on the \(z = 0\) plane). This parabola opens upwards, and the vertex is at the origin, \((0, 0, 0)\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Parabola
A parabola is a U-shaped curve that can open upwards, downwards, left, or right. In the context of coordinate geometry, a parabola is typically described by a quadratic equation. The equation given in the exercise, \( y = x^2 \), represents a parabola opening upwards. This specific parabola is symmetrical about the y-axis and has its vertex at the origin - Vertex: The point where the parabola changes direction, located at \((0,0)\). This is the parabolic vertex.- Axis of symmetry: The vertical line \( x = 0 \) is the line of symmetry for this parabola.- Opening direction: In the equation \( y = x^2 \), since the coefficient of \( x^2 \) is positive, the parabola opens upwards.Understanding the geometric properties of a parabola helps visualize the shape and position of points satisfying the given equation.
Coordinate Geometry
Coordinate geometry, also known as analytic geometry, is the study of geometry using a coordinate system. This enables precise manipulation of geometric shapes through algebraic equations. In this exercise, coordinate geometry allows us to describe and analyze the parabola \( y = x^2 \) as a set of points in the plane.- Coordinates: A pair \( (x,y) \) denotes a specific point on the parabola in the coordinate plane.- Plane: In two dimensions, this system uses the x and y-axis to locate points.Using coordinate geometry, one can transform geometric problems into algebraic equations, making it easier to solve and understand the shapes and their properties.
xy-plane
The xy-plane is a two-dimensional flat surface that extends infinitely in the x and y directions. In three-dimensional space, the xy-plane is defined by setting the z-coordinate to zero for all its points. It serves as a fundamental plane in mathematics and is used extensively in various fields for plotting and graphing.- Definition: All points in the xy-plane have the form \((x, y, 0)\).- Role: It acts as a reference plane for plotting graphs and equations, such as the parabola \( y = x^2 \) in this exercise.Given the condition \( z = 0 \), all points of the parabola sit flat on the xy-plane. This restriction ensures the parabola lies entirely within two-dimensional space, providing a clear geometric representation.
Three-Dimensional Space
Three-dimensional space is a mathematical extension of the concept of two-dimensional xy-plane, adding the z-axis for depth. While the given exercise confines itself to the xy-plane, understanding three-dimensional space helps contextualize the role of the z-coordinate.- Dimensions: Involves three axes: x, y, and z.- Representation: Points are denoted as \((x, y, z)\), showing their position across all three dimensions.In this exercise, the equation \( z = 0 \) restricts points to the xy-plane, meaning they have no depth or elevation in the z-direction. Recognizing the distinction between these planes ensures that the geometric structure, like the parabola described, is correctly interpreted whether in two or three dimensions.