Chapter 2: Problem 13
Find a parametrization of the line in \(\mathbb{R}^{3}\) that passes through the point \(\mathbf{a}=(1,2,3)\) and is parallel to \(\mathbf{v}=(4,5,6)\)
Short Answer
Expert verified
\( \mathbf{r}(t) = (1 + 4t, 2 + 5t, 3 + 6t) \)
Step by step solution
01
Understand the line parametrization in 3D
A line in three-dimensional space can be parametrized as \( \mathbf{r}(t) = \mathbf{a} + t\mathbf{v} \), where \( \mathbf{a} \) is a point on the line and \( \mathbf{v} \) is the direction vector. The parameter \( t \) is a scalar that varies over all real numbers.
02
Identify the given elements
We are given the point \( \mathbf{a} = (1, 2, 3) \) and the direction vector \( \mathbf{v} = (4, 5, 6) \). These will be used to construct the parametrization expression.
03
Construct the parametrization
Substitute the given point and direction vector into the parametrization formula. The resulting expression is \( \mathbf{r}(t) = (1, 2, 3) + t(4, 5, 6) \).
04
Simplify the expression
Expand the expression to write the parametrization in component form: \( \mathbf{r}(t) = (1 + 4t, 2 + 5t, 3 + 6t) \). This is the parametrization of the line in \( \mathbb{R}^3 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Direction Vector
In the context of three-dimensional geometry, a direction vector is essential in defining a line. Think of it as the compass needle that guides the path along which the line extends.
This vector, typically denoted as \( \mathbf{v} \), indicates the direction of the line, and it plays a crucial role when parametrizing a line in space.
Without the direction vector, you wouldn't know which direction your line is heading!
This vector, typically denoted as \( \mathbf{v} \), indicates the direction of the line, and it plays a crucial role when parametrizing a line in space.
- It tells you how the line stretches in space along each axis.
- The vector components show how much the line moves in the x, y, and z directions with each step of change in the parameter \( t \).
Without the direction vector, you wouldn't know which direction your line is heading!
Point in Space
A point in space, represented as \( \mathbf{a} = (x_1, y_1, z_1) \), serves a foundational role when defining a line in three-dimensional space.
This point is a specific location that your line will pass through. It works in tandem with the direction vector to anchor the line to a specific starting point in space.
This point ensures that every resulting coordinate on the line is traced back to starting here.
This point is a specific location that your line will pass through. It works in tandem with the direction vector to anchor the line to a specific starting point in space.
- You can think of the point \( \mathbf{a} \) as the fixed point where the line touches "reality," giving it a concrete position.
- In the equation for line parametrization, this point gives the initial position of the line before any scaling or direction is considered via the parameter \( t \).
This point ensures that every resulting coordinate on the line is traced back to starting here.
Line in Three-Dimensional Space
Defining a line in three-dimensional space involves bringing together the concepts of a point and a direction vector through the use of parametrization.
This creates a mathematical representation that describes an infinite set of points lying on the line as determined by changing a single variable, usually \( t \).
As \( t \) shifts, the position changes along the vector's direction, effectively plotting an infinite number of points on the line.
This creates a mathematical representation that describes an infinite set of points lying on the line as determined by changing a single variable, usually \( t \).
- The standard formula to define such a line is \( \mathbf{r}(t) = \mathbf{a} + t\mathbf{v} \).
- Here, \( \mathbf{a} \) represents the starting point, while \( \mathbf{v} \) indicates the direction.
- By varying \( t \), you can obtain every possible point on the line in space.
As \( t \) shifts, the position changes along the vector's direction, effectively plotting an infinite number of points on the line.