There are 1 questions in this calculation: for each question, the 1 derivative of t is calculated.
    Note that variables are case sensitive.
\[ \begin{equation}\begin{split}[1/1]Find\ the\ first\ derivative\ of\ function\ \frac{rcos(nt)}{t} + \frac{rsin(nt)}{t}\ with\ respect\ to\ t：\\\end{split}\end{equation} \]\[ \begin{equation}\begin{split}\\Solution:&\\ &Primitive\ function\ = \frac{rcos(nt)}{t} + \frac{rsin(nt)}{t}\\&\color{blue}{The\ first\ derivative\ function：}\\&\frac{d\left( \frac{rcos(nt)}{t} + \frac{rsin(nt)}{t}\right)}{dt}\\=&\frac{r*-cos(nt)}{t^{2}} + \frac{r*-sin(nt)n}{t} + \frac{r*-sin(nt)}{t^{2}} + \frac{rcos(nt)n}{t}\\=&\frac{-rcos(nt)}{t^{2}} - \frac{rnsin(nt)}{t} - \frac{rsin(nt)}{t^{2}} + \frac{rncos(nt)}{t}\\ \end{split}\end{equation} \]

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