Difficulty: Easy
Correct Answer: 1 / (s^2 + 1)
Explanation:
Introduction / Context:
The Laplace transform converts time-domain signals to the s-domain, simplifying differential equations to algebraic forms. Trigonometric inputs such as sin t and cos t are classics, and remembering their transforms is essential for solving control and circuit problems quickly.
Given Data / Assumptions:
Concept / Approach:
The standard Laplace transform of sin(ω t) is ω / (s^2 + ω^2). Setting ω = 1 yields 1 / (s^2 + 1). This can also be derived via integration using Euler’s identities or by differentiating the transform of cos t with respect to s.
Step-by-Step Solution:
Verification / Alternative check:
Differentiate the transform pair L{cos t} = s / (s^2 + 1) with respect to s and apply relationships between sin and cos to reconfirm the result.
Why Other Options Are Wrong:
Common Pitfalls:
Swapping the transforms of sin t and cos t; remember sin has numerator ω, cos has numerator s.
Final Answer:
1 / (s^2 + 1)
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