$f(x,y)=9-x^2-y^2$ and $\vec r(t)=(2\cos t, 3\sin t)$. Imagine
    the following scenario: a horse runs around outside in the
    cold. The horse's position at time $t$ is given parametrically
    by the elliptical path $\vec r(t)$. The function $T=f(x,y)$
    gives the temperature of the air at any point $(x,y)$.

    <ol>
      <li id="horse-track-item-1">At time $t=0$, what is the horse's
      position $\vec r(0)$, and what is the temperature $f(\vec
      r(0))$ at that position? Find the temperatures 