X0IcsT9FhSrUTJEeZfqELUxuVZdR9bzmKjoiZ9tZmc-b7HwLuU4W7nzVcP9UJ7rCBjh6KOrihM8IHUhuxpg_nszGWwKSn5Vtf946meRCydww1iAROGHEZ6yP4atEiOmtQnjRa9PlqfFubNaxfC1Xc92cfdaoLAVSX-A1SMc_Q">
      Sage</a>.</div>
          Draw the 3D surface plot of $f$. In the
      $xy$-plane of your 3D plot (so $z=0$) add the path of the
      horse. In class, we'll project the path of the horse up into
      the 3D surface.</li>
    </ol>
  </div>

  <div class="problem">
    Consider again $f(x,y)=9-x^2-y^2$ and $\vec r(t)=(2\cos t,
   