<exercise>
<statement>
<p>
Draw a phase plane for the following system of ODEs.
</p>
<me>x'=<xsl:value-of select="dxdt"/></me>
<me>y'=<xsl:value-of select="dydt"/></me>
<p>Be sure to include and label the following features in your sketch:</p>
<ul>
<li>The isoclines <m>x'=0</m> and <m>y'=0</m>.</li>
<li>Arrow systems describing trajectories of solutions.</li>
<li>The equillibrium of the system.</li>
</ul>
</statement>
<answer>
<p>
The isoclines cross at the equillibrium <m><xsl:value-of select="intersection"/></m>,
with <m>x'=0</m> having a <xsl:value-of select="dxdt_slope"/> slope
and <m>y'=0</m> having a <xsl:value-of select="dydt_slope"/> slope.
</p>
<p>
The right region has a <xsl:value-of select="right_arrows"/> arrow system,
the top region has a <xsl:value-of select="top_arrows"/> arrow system,
the left region has a <xsl:value-of select="left_arrows"/> arrow system, and
the bottom region has a <xsl:value-of select="bottom_arrows"/> arrow system.
</p>
</answer>
</exercise>
