// Numbas version: exam_results_page_options {"name": "Ugur's copy of Laplace transform #2 - Trig functions", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "Ugur's copy of Laplace transform #2 - Trig functions", "tags": [], "metadata": {"description": "", "licence": "Creative Commons Attribution-NonCommercial 4.0 International"}, "statement": "

What is the Laplace transform for the function:

\n

\\(x(t)=\\var{a}\\sin({\\var{n}t})+\\var{b}\\cos({\\var{k}t}).\\)

\n

", "advice": "

By the linearity of Laplace Transform:

\n

\\[X(s)=\\mathcal L\\{\\var{a}\\sin({\\var{n}t})+\\var{b}\\cos({\\var{k}t})\\} = \\var{a}\\mathcal L\\{\\sin({\\var{n}t})\\}+\\var{b}\\mathcal L\\{\\cos({\\var{k}t})\\}.\\]

\n

From Laplace Transform table one can read 

\n

\\[\\mathcal L\\{\\sin({\\var{n}t})\\} = \\frac{\\var{n}}{s^2 + \\var{n}^2} \\quad \\mbox{ and } \\quad \\mathcal L\\{\\cos({\\var{n}t})\\} = \\frac{s}{s^2 + \\var{k}^2}.\\] 

\n

Hence 

\n

\\[X(s)=\\mathcal L\\{\\var{a}\\sin({\\var{n}t})+\\var{b}\\cos({\\var{k}t})\\} = \\var{a}\\mathcal L\\{\\sin({\\var{n}t})\\}+\\var{b}\\mathcal L\\{\\cos({\\var{k}t})\\} = \\frac{\\simplify{{a}*{n}}}{s^2 + \\simplify{{n}^2}} + \\frac{\\var{b}s}{s^2 + \\simplify{{k}^2}}.\\]

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\\(X(s)=\\) [[0]]

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