Chapter 12: Problem 54
Find the indefinite integral. $$ \int\left(e^{t} \mathbf{i}+\sin t \mathbf{j}+\cos t \mathbf{k}\right) d t $$
Short Answer
Expert verified
The indefinite integral of the given function is \( e^{t} \mathbf{i} - \cos t \mathbf{j} + \sin t \mathbf{k} + C \)
Step by step solution
01
Break into Components
Break the integral function into its individual components. Each component is related to a unit vector, \( \mathbf{i} \), \( \mathbf{j} \), \( \mathbf{k} \). These are three separate integrals that need to be calculated independently.
02
Integral of first Component
The first component is \( \int e^{t} dt \). The function \( e^{t} \) when integrated with respect to \( t \), gives \( e^{t} \). Hence, the integrated component corresponding to \( \mathbf{i} \) is \( e^{t} \mathbf{i} \).
03
Integral of second component
The second component is \( \int \sin t dt \). The function \( \sin t \) gives \( -\cos t \) upon integration. Therefore, the component corresponding to \( \mathbf{j} \) would be \( -\cos t \mathbf{j} \).
04
Integral of third Component
The third component is \( \int \cos t dt \). The integral of \( \cos t \) is \( \sin t \). Thus, the integrated component related to \( \mathbf{k} \) is \( \sin t \mathbf{k} \).
05
Sum of components
Combine all the components together to get the final answer. Don't forget to add the constant of integration, \( C \), to the solution after performing the integration.
06
Write the final answer
The final indefinite integral of the given vector-valued function is therefore \( e^{t} \mathbf{i} - \cos t \mathbf{j} + \sin t \mathbf{k} + C \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Integration by Components
Integration by parts is a powerful integration technique used when dealing with products of functions. While we might think it is directly linked to this problem, the method used here involves breaking down a vector-valued function into simpler components. Each part is integrated separately.
This isn't the classic integration by parts method which relies on the formula:
This isn't the classic integration by parts method which relies on the formula:
- \(\int u\, dv = uv - \int v\, du\)
- The exponential function \(e^t\) integrates to itself: \(\int e^{t} dt = e^{t}\).
- The trigonometric functions \(\sin t\) and \(\cos t\) integrate to \(-\cos t\) and \(\sin t\) respectively.
Vector-Valued Functions
Vector-valued functions assign a vector to each element in their domain. In the context of this exercise, we have the function \( e^{t} \mathbf{i} + \sin t \mathbf{j} + \cos t \mathbf{k} \). Each component ties to a direction in the 3-dimensional space represented by \(\mathbf{i}, \mathbf{j}, \mathbf{k}\).
Here's how you understand them:
Here's how you understand them:
- \(\mathbf{i}, \mathbf{j}, \mathbf{k}\) are unit vectors pointing in the direction of x, y, and z axes respectively.
- The function value at each \( t \) is a vector made up of three scalar components.
- The x-component (\( e^{t} \mathbf{i} \)) moves along the \(\mathbf{i}\) direction.
- The y-component (\( \sin t \mathbf{j} \)) is governed by the \(\mathbf{j}\) direction.
- The z-component (\( \cos t \mathbf{k} \)) follows the \(\mathbf{k}\) direction.
Constant of Integration
In the context of indefinite integrals, the constant of integration \( C \) arises due to the nature of antiderivatives. When performing an indefinite integration, the set of all antiderivatives of a function includes a constant term. This term accounts for any constant that, when differentiated, results in zero.
Therefore:
Therefore:
- After integrating a function like \( f(x) \), the result is \( F(x) + C \).
- This signifies that there are infinitely many antiderivatives for any given function, distinguished only by a constant difference.
- Each scalar component, when integrated, has its own constant of integration.
- For the final vector, it unifies as a singular constant \( C \), representing a vector of constants for each dimension.