[tex]\bf s(t)=\cfrac{5t}{sin(t)}[/tex]
a rational expression is asymptotic, when the expression becomes undefined, and that happens when the denominator is 0, or turns to 0
the vertical asymptote is there, only if such value, turns the denominator to 0, whilst not zeroing out the numerator
well, for sine, that is at [tex]\bf -\infty...0,\pi , 2\pi ,3\pi ,4\pi ....+\infty
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thus\implies 0\pm \pi n\quad \textit{"n" being an integer}[/tex]