Chapter 12: Problem 38
Sketch the curve of intersection of the surfaces, and find a vector equation for the curve in terms of the parameter x = t. $$ y=x, x+y+z=1 $$
Short Answer
Expert verified
The vector equation is \(\mathbf{r}(t) = \langle t, t, 1 - 2t \rangle\).
Step by step solution
01
Identify the Surfaces
We have two surfaces: a plane defined by the equation \(x+y+z=1\) and another surface defined by the equation \(y=x\). Our task is to find and sketch the curve of intersection of these surfaces.
02
Substitute y with x
Since the equation \(y=x\) implies that for every point on the curve \(y\) can be replaced with \(x\), we substitute \(y\) with \(x\) in the plane equation: \(x + x + z = 1\). This simplifies to \(2x + z = 1\).
03
Express z in terms of x
Solve the equation \(2x + z = 1\) for \(z\). This gives us \(z = 1 - 2x\). Now, both \(y\) and \(z\) are expressed in terms of \(x\).
04
Introduce the Parameter t
Let \(x = t\), which serves as our parameter. Thus, \(y = t\) and \(z = 1 - 2t\).
05
Write the Vector Equation
Combine the parameterized coordinates into a vector equation of the curve. The vector equation is \(\mathbf{r}(t) = \langle t, t, 1 - 2t \rangle\), which describes the curve of intersection.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vector Equation
A vector equation provides a way to describe a curve or a line in space using a vector format. It's quite useful when dealing with problems in 3D space, such as the one we have here, intersecting a plane and a line. In our exercise, we arrived at the vector equation by expressing all the coordinates (x, y, z) in terms of a single parameter.
- The parameter here is often denoted by 't'.
- It gives us a simple and flexible way to represent the entire curve.
Parameterization
Parameterization is a method of expressing a set of quantities as functions of one or more independent variables, known as parameters. In the context of our problem, parameterization involves using a single parameter 't' to express all the variables that define the curve of intersection.
- Here, we chose the parameter 'x' to be equal to 't', which simplifies our problem.
- By letting \( y = t \) and \( z = 1 - 2t \), we effectively map the curve.
Plane Equation
The plane equation in this problem is given by \( x + y + z = 1 \). This is a classic representation of a plane in 3-dimensional space. To intersect with another surface, like the line described by \( y = x \), we substitute variables to find a common solution.
- Each coefficient in the equation has a geometric interpretation, aligning with the plane's orientation in 3D space.
- The constant term, 1, indicates the plane's position relative to the origin.
Surface Intersection
Surface intersection involves finding a common region, or curve, formed by the overlap of two surfaces. In our case, we're intersecting a plane with a line, which mathematically translates into a specific curve that we can describe using parameterization.
- The intersection curve contains all points that satisfy both surface equations simultaneously.
- By utilizing parameterization, we conveniently express this curve to understand its shape and trajectory.