Laplace Transform simpilification

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SUMMARY

The discussion focuses on the simplification of the Laplace transform for the expression involving the term re^{-mt} \cos(pt + q). The user successfully solved the problem for specific values of q (0 and π/2) but struggled with the general case. By applying the cosine expansion identity, the expression can be rewritten as re^{-mt} [\cos(pt)\cos(q) - \sin(pt)\sin(q)], allowing for the use of standard Laplace transform tables to find the solution.

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  • Understanding of Laplace transforms
  • Familiarity with trigonometric identities, specifically the cosine expansion identity
  • Knowledge of standard Laplace transform tables
  • Basic calculus concepts related to differential equations
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gnittel
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Homework Statement



Is there a simplified Laplace transform of
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The Attempt at a Solution



This is actually a three part question, I was only able to solve it when q is 0 or pi/2. but i can't seem to figure out the general solution.
 
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You could apply the cosine expansion identity to get:

[tex] re^{ - mt} \cos (pt + q) \equiv re^{ - mt} [\cos (pt)\cos (q) - \sin (pt)\sin (q)][/tex]

In which case it should now be easy to use a standard table of laplace transforms to get the answer you are looking for.

(I am assuming that r, m, p and q are all constants)
 

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