Chapter 13: Problem 27
Find an equation for the plane through the origin containing the points (1,3,0) and (2,4,1)
Short Answer
Expert verified
The equation of the plane is \(3x - y - 2z = 0\).
Step by step solution
01
Identify the Normal Vector
To find the equation of a plane, we need a normal vector. First, identify two vectors lying on the plane using the given points. The vectors can be defined as \( \mathbf{a} = (1,3,0) \) and \( \mathbf{b} = (2,4,1) \). The normal vector \( \mathbf{n} \) is obtained by the cross product of \( \mathbf{a} \) and \( \mathbf{b} \).
02
Compute the Cross Product
The cross product \( \mathbf{n} = \mathbf{a} \times \mathbf{b} \) is calculated as follows: \[\mathbf{n} = \begin{vmatrix}\mathbf{i} & \mathbf{j} & \mathbf{k} \1 & 3 & 0 \2 & 4 & 1\end{vmatrix} = \mathbf{i}(3 \cdot 1 - 0 \cdot 4) - \mathbf{j}(1 \cdot 1 - 0 \cdot 2) + \mathbf{k}(1 \cdot 4 - 3 \cdot 2)\]\[= \mathbf{i} (3) - \mathbf{j} (1) + \mathbf{k} (-2) = (3, -1, -2)\]
03
Write the Equation of the Plane
The general equation of a plane is given by \( ax + by + cz = d \). Given that our plane passes through the origin \((0,0,0)\), \(d = 0\). Substitute \((a, b, c) = (3, -1, -2)\):\[ 3x - y - 2z = 0 \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Cross Product
In three-dimensional space, the cross product is a useful operation to find a vector that is perpendicular to two given vectors. This is particularly useful when determining the normal vector for a plane, as in the above exercise.
- The cross product of two vectors \( \mathbf{a} = (a_1, a_2, a_3) \) and \( \mathbf{b} = (b_1, b_2, b_3) \) is denoted as \( \mathbf{a} \times \mathbf{b} \).
- It results in a new vector \( \mathbf{n} = (n_1, n_2, n_3) \), where each component is derived from the determinant of a matrix involving \( \mathbf{i}, \mathbf{j}, \mathbf{k} \), the unit vectors.
- The formula is:\[\mathbf{n} = \begin{vmatrix}\mathbf{i} & \mathbf{j} & \mathbf{k} \ a_1 & a_2 & a_3 \ b_1 & b_2 & b_3\end{vmatrix} \]
- Each component \( n_1, n_2, n_3 \) is calculated as a minor determinant of the matrix, influenced by switching certain elements.
Normal Vector
A normal vector to a plane is essential for defining the orientation or "tilt" of that plane in three-dimensional space. It is a vector perpendicular to every vector lying in the plane.
- Once you have a normal vector \( \mathbf{n} \), you can uniquely determine the equation of the plane.
- In our context, the normal vector comes from the cross product of two non-parallel vectors lying on the plane.
- It can be represented as \( \mathbf{n} = (a, b, c) \), with these three coefficients defining the plane equation \( ax + by + cz = d \).
Vectors in 3D
Vectors in 3D space are essential mathematical tools that allow for the representation and manipulation of objects in three-dimensional physics and geometry.
- A vector in 3D is expressed in the form \( \mathbf{v} = (x, y, z) \), with each component indicating the vector's magnitude along the x, y, and z axes.
- Vectors can be visualized as arrows where direction and magnitude are clearly represented, enabling one to consider geometric properties and relationships.
- Both addition and subtraction of vectors are straightforward, treating isotonic components (x with x, y with y, etc.).
- When dealing with planes, any two non-parallel vectors lying on the plane can be used to calculate a normal vector, to define that plane.