Learn more about the geometry of \(\vert \vec{r}-\vec{r'}\vert\) in two dimensions.
Make a sketch of the graph \begin{equation*} \vert \vec{r} - \vec{a} \vert = 2 \end{equation*}
for each of the following values of \(\vec a\): \begin{align*} \vec a &= \vec 0\\ \vec a &= 2 \hat x- 3 \hat y\\ \vec a &= \text{points due east and is 2 units long} \end{align*}