Added pi

main.html

@@ -87,7 +87,7 @@
         <dt>Functions:</dt>
         <dd>sin, cos, tan, sqrt, log10, log2, ln, arccos, arcsin, arctan, abs </dd>
         <dt>Constants</dt>
-        <dd>e</dd>
+        <dd>e, pi</dd>
 
        <!-- Students won't know what parallel means at this time.  Complex numbers aren't well tested in the courseware, so we would prefer to not expose them.  If you read the comments in the source, feel free to use them. If you run into a bug, please let us know. But we can't officially support them right now.