Chapter 8: Problem 637
Given initial point \(P_{1}=(3,2)\) and terminal point \(P_{2}=(-5,-1),\) write the vector \(v\) in terms of \(i\) and \(j .\) Draw the points and the vector on the graph.
Short Answer
Expert verified
The vector is \(-8\mathbf{i} - 3\mathbf{j}\).
Step by step solution
01
Determine the Vector Components
To find the vector \( \mathbf{v} \) from point \( P_1 = (3, 2) \) to point \( P_2 = (-5, -1) \), we calculate the components of \( \mathbf{v} \). The change in the x-coordinates is \( \Delta x = x_2 - x_1 = -5 - 3 = -8 \). Similarly, the change in the y-coordinates is \( \Delta y = y_2 - y_1 = -1 - 2 = -3 \). Thus, the vector components are \( i = -8 \) and \( j = -3 \).
02
Express the Vector in Terms of i and j
Once we have the components, we can express the vector \( \mathbf{v} \) in terms of the unit vectors \( \mathbf{i} \) and \( \mathbf{j} \). Using the components from Step 1, the vector is \( \mathbf{v} = -8\mathbf{i} - 3\mathbf{j} \).
03
Draw the Vector on the Graph
To graph the vector, plot the initial point \( P_1 = (3, 2) \) and the terminal point \( P_2 = (-5, -1) \) on the coordinate plane. Draw the vector \( \mathbf{v} \) starting at \( P_1 \) and ending at \( P_2 \). The vector should point from \( (3, 2) \) to \( (-5, -1) \). You can extend a straight arrow from \( P_1 \) to \( P_2 \) to represent the direction and magnitude of \( \mathbf{v} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vector Components
When we talk about vector components, we are referring to how a vector can be broken down into its basic parts: the horizontal and vertical changes (movements) in a coordinate plane. Every vector has an initial point where it starts and a terminal point where it ends. The difference between these points in the x-direction and y-direction gives us the components of the vector.
To find these components, you simply subtract the coordinates of the initial point from the terminal point. For example:
To find these components, you simply subtract the coordinates of the initial point from the terminal point. For example:
- For a vector going from point \( P_1 = (3, 2) \) to point \( P_2 = (-5, -1) \), the x-component is calculated as \( \Delta x = x_2 - x_1 = -5 - 3 = -8 \).
- Similarly, the y-component is \( \Delta y = y_2 - y_1 = -1 - 2 = -3 \).
Coordinate Geometry
Coordinate geometry, also known as analytic geometry, is all about using a coordinate system to investigate geometric shapes' properties and relations. It's like graphing meets algebra—using coordinates and formulas to solve problems about shapes and lines.
When dealing with vectors on a coordinate plane, coordinate geometry allows you to visually interpret the movement or direction represented by the vector. In our example:
When dealing with vectors on a coordinate plane, coordinate geometry allows you to visually interpret the movement or direction represented by the vector. In our example:
- The initial point \( P_1 = (3, 2) \) and terminal point \( P_2 = (-5, -1) \) are plotted on the coordinate axis.
- The vector \( \mathbf{v} \) can then be drawn as an arrow between these points.
Unit Vectors
Unit vectors are special vectors with a magnitude of exactly one unit. They are used to express directions and are fundamental in decomposing vectors into their components. In two-dimensional space, we primarily use two unit vectors: \( \mathbf{i} \) and \( \mathbf{j} \), which represent unit movement along the x-axis and y-axis, respectively.
In terms of writing any vector as a combination of these unit vectors, you take the x-component and match it with \( \mathbf{i} \), and the y-component with \( \mathbf{j} \). For instance, for a vector \( \mathbf{v} = -8 \mathbf{i} - 3 \mathbf{j} \):
In terms of writing any vector as a combination of these unit vectors, you take the x-component and match it with \( \mathbf{i} \), and the y-component with \( \mathbf{j} \). For instance, for a vector \( \mathbf{v} = -8 \mathbf{i} - 3 \mathbf{j} \):
- The x-component of -8 is paired with \( \mathbf{i} \), meaning it moves 8 units in the negative x-direction.
- The y-component of -3 is paired with \( \mathbf{j} \), meaning it moves 3 units in the negative y-direction.