will the wind keep pushing me in the
    same direction? Will it get stronger or weaker?
  </div>

  <div class="problem" id="derivative-practice">
    <div class="marginpar">
      Use <a href=
      "http://sagecell.sagemath.org/?z=eJwr0ijVKdO0BZE6pVrJ-cUaZZqavFy8XAVFmXklCkohGakKKalFmWWJJZllqQqZxUogySK9lMy0NA1NsGYAokcTpg==&amp;lang=sage">
      Sage</a> to check your work in each part.
    </div>Do the following for each of the functions below:

    <ul>
      <li>Compute the partial derivatives and the t