Chapter 7: Problem 23
Find parametric equations for the line through \((6,4,-2)\) that is parallel to the line \(x / 2=(1-y) / 3=(z-5) / 6\).
Short Answer
Expert verified
The parametric equations are \( x = 6 + 2t, y = 4 - 3t, z = -2 + 6t \).
Step by step solution
01
Understand the given line
The given line is presented in its symmetric form: \( \frac{x}{2} = \frac{1-y}{3} = \frac{z-5}{6} \). The symmetric form can be separated into three equations that describe the parameterization. By recognizing this, we can identify the direction vector of the line, which is \( \langle 2, -3, 6 \rangle \).
02
Identify a point and direction vector
We need a direction vector that is parallel to the given line. From Step 1, we know the direction vector of the given line is \( \langle 2, -3, 6 \rangle \). We also have a point through which our line passes, \((6,4,-2)\).
03
Write the parametric equations
Using the direction vector \( \langle 2, -3, 6 \rangle \) and the point \((6, 4, -2)\), the parametric equations of the line can be constructed. The parametric equations are: \[x = 6 + 2t\,y = 4 - 3t\,z = -2 + 6t\] where \( t \) is the parameter.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Symmetric Form
The symmetric form of a line in three-dimensional space beautifully compacts three equations into a single expression. Imagine having these expressions: \( \frac{x}{a} = \frac{b-y}{d} = \frac{z-c}{f} \). This expression reveals the relationship between variables on the line.
The behavior of a line in space is connected to its symmetric form through:
The behavior of a line in space is connected to its symmetric form through:
- It shows proportional relationships among the coordinates.
- It hints at the direction of the line with the denominators \(a, d, f\).
- These values \(2, -3, 6\) act as the direction vector components.
- They indicate how each axis changes.
Direction Vector
The direction vector is the secret compass of a line in space. For a line, it shows how the line extends.
In the symmetric form, the direction vector is clear from the denominators: \( \langle a, d, f \rangle \) or specifically \( \langle 2, -3, 6 \rangle \) for our example. This vector:
In the symmetric form, the direction vector is clear from the denominators: \( \langle a, d, f \rangle \) or specifically \( \langle 2, -3, 6 \rangle \) for our example. This vector:
- Describes the line's direction.
- Is unaffected by starting points.
- Using the direction vector ensures parallelism.
- Varying only the start point gives a new line.
Line Equations
Bringing lines to life in space involves writing their equations. Lines in 3D have favorable representations, like parametric equations. Given a direction vector \( \langle a, d, f \rangle \) and a specific point \((x_0, y_0, z_0)\):
The line's parametric equations become:
\[ x = x_0 + at, \, y = y_0 + dt, \, z = z_0 + ft \]
In our example, using point \((6, 4, -2)\) and direction vector \( \langle 2, -3, 6 \rangle \):
\[ x = 6 + 2t, \, y = 4 - 3t, \, z = -2 + 6t \]
Where \( t \) is a real number. This gives a powerful way to trace any point along the line with varying \( t \). Lines can be:
The line's parametric equations become:
\[ x = x_0 + at, \, y = y_0 + dt, \, z = z_0 + ft \]
In our example, using point \((6, 4, -2)\) and direction vector \( \langle 2, -3, 6 \rangle \):
\[ x = 6 + 2t, \, y = 4 - 3t, \, z = -2 + 6t \]
Where \( t \) is a real number. This gives a powerful way to trace any point along the line with varying \( t \). Lines can be:
- Infinite with respect to the parameter \( t \).
- Customized with different starting points but consistent directions.
Vectors in Space
Vectors in space form the backbone of how we navigate through three dimensions. They represent more than just points; they convey *direction and magnitude*.
Key features include:
Key features include:
- Describing positions, directions, and displacements.
- Characterization with components like \( \langle x, y, z \rangle \).
- Indicate the movement's direction using components.
- Without starting point restrictions, define infinite parallel lines.