ned by
<span class="math display">\[
R_{\theta}
=
\begin{bmatrix}
\cos \theta &amp; - \sin \theta
\\
\sin \theta &amp; \cos \theta
\end{bmatrix}.
\]</span>
Given a two-dimensional vector <span class="math inline">\(x\)</span>, <span class="math inline">\(R_{\theta} \, x\)</span> is the rotation
of <span class="math inline">\(x\)</span> (around the origin) by <span class="math inline">\(\theta\)</span> degrees.</p>
<div id="unit-vector-type" class="section level3 unnumbered">
<h3>Unit vector type</h3>
<p>In 