Chapter 3: Problem 8
Use the given equation of a line to find a point on the line and a vector parallel to the line. \(\mathbf{x}=(1-t)(0,-5,1)\)
Short Answer
Expert verified
A point on the line is (0, -5, 1), and a vector parallel to the line is (0, -5, 1).
Step by step solution
01
Identify Parametric Equation Components
The given equation of the line is in the form \( \mathbf{x} = (1-t)(0,-5,1) \). This is a parametric equation where \( t \) is the parameter. Here, the components \((0, -5, 1)\) represent the direction vector of the line.
02
Determine a Vector Parallel to the Line
The vector parallel to the line can be directly taken from the equation. The direction vector given by \((0, -5, 1)\) is a vector that is parallel to the line. This vector provides the direction in which the line extends.
03
Calculate a Specific Point on the Line
To find a specific point on the line, we can choose a parameter value. Let's set \( t = 0 \). Substituting \( t = 0 \) into the equation, we get: \( \mathbf{x} = (1-0)(0,-5,1) = (0, -5, 1) \). Hence, the point \((0, -5, 1)\) lies on the line.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vector Mathematics
Vector mathematics is a branch of mathematics that deals primarily with vectors, which are geometric entities characterized by a magnitude and a direction. In the context of three-dimensional space, vectors are often represented in component form, such as \(\mathbf{v} = (a,b,c)\). This representation helps to highlight each directional influence along the x, y, and z axes.
- Magnitude of a Vector: The magnitude or length of a vector \(\mathbf{v}\) is denoted as \(|\mathbf{v}|\) and can be calculated using the formula \(|\mathbf{v}| = \sqrt{a^2 + b^2 + c^2}\).
- Addition and Subtraction: Vectors can be added or subtracted component-wise. For example, given two vectors \(\mathbf{u} = (a_1, b_1, c_1)\) and \(\mathbf{v} = (a_2, b_2, c_2)\), their sum is \(\mathbf{u} + \mathbf{v} = (a_1 + a_2, b_1 + b_2, c_1 + c_2)\).
- Scalar Multiplication: Multiplying a vector by a scalar changes its magnitude but not its direction, provided the scalar is positive. If \( ext{scalar} = k\), then \(k \mathbf{v} = (ka, kb, kc)\).
Direction Vector
A direction vector is a crucial concept in vector mathematics, serving as a pointer indicating the direction in which a line extends. The direction vector is key to identifying or specifying the orientation of a line in space.
- Representation in Parametric Equations: In parametric equations of the form \(\mathbf{x} = \mathbf{p} + t\mathbf{d}\), \(\mathbf{d}\) is often the direction vector. This vector does not change with the parameter \(t\), and its role is to establish the line’s orientation.
- Determination of Direction: The direction vector is derived from the coefficients of the line in its vector equation. In our exercise, \(\mathbf{x}=(1-t)(0,-5,1)\), the direction vector is clearly \((0, -5, 1)\), showing no movement along the x-axis, downward movement in the y-axis, and upwards movement in the z-axis.
Point on a Line
A line in three-dimensional space can be represented using parametric equations, and it can pass through numerous points. To find a specific point on a line, we use the parametric equation of the line, which includes a parameter that can be varied to yield different points along the line.
- Using the Parameter: In this context, setting a specific value for the parameter \(t\) allows us to identify a distinct point on the line. For example, the equation \(\mathbf{x}=(1-t)(0,-5,1)\) will let us find specific points for different \(t\) values.
- Example: Setting \(t = 0\) in our exercise yields the point \((0, -5, 1)\), showing us a tangible position on the line. As \(t\) varies, so does the location of the calculated point, illustrating the infinite number of possible positions a line can pass through.