\usepackage{pgfplots}
\usepackage{pst-plot}
\usepackage{rotating}
+%\usepackage{showframe} % debugging only
\usepackage{subfiles}
\usepackage{tabularx}
\usepackage{tcolorbox}
\end{align*}
\noindent \textbf{Distance travelled between \(t=a \rightarrow t=b\):}
- \[= \int^b_a \sqrt{\left(\frac{dx}{dt}\right)^2 + \left(\frac{dy}{dt}\right)^2} \cdot dt \]
+ \begin{align*}
+ &= \int^{b}_{a}{\sqrt{\left(\frac{dx}{dt}\right)^2 + \left(\frac{dy}{dt}\right)^2}} \> dt \tag{2D} \\
+ &= \int^{t=b}_{t=a}{\dfrac{dx}{dt}} \> dt \tag{linear}
+ \end{align*}
\noindent \textbf{Shortest distance between \(\boldsymbol{r}(t_0)\) and \(\boldsymbol{r}(t_1)\):}
\[ = |\boldsymbol{r}(t_1) - \boldsymbol{r}(t_2)| \]