an <em>x</em> axis, a <em>y</em> axis, and a linear unit of measure.</p></li>
<li><p>Going from a GCS to a PCS requires mathematical transformations.</p></li>
<li><p>There are three main groups of projection types:</p>
<ul>
<li><strong>conic</strong>:
<ul>
<li>defined by a cone touching the earth at 1 or 2 lines of tangency</li>
<li>best suited for mid-latitude areas</li>
</ul></li>
<li><strong>cylindrical</strong>:
<ul>
<li>defined by a cylinder touching the earth at 1 or 2 lines of tangency</li>
<li>best 