PG problem file Explanation
DOCUMENT();
"PGstandard.pl",
"MathObjects.pl",
"parserImplicitPlane.pl",
);
TEXT(beginproblem());

Initialization: We need to include the macros file AnswerFormatHelp.pl.

Context("ImplicitPlane")->variables->are(x=>"Real",y=>"Real");

Setup: By declaring there are only two variables, ImplicitPlane will address objects as lines rather than planes.

BEGIN_TEXT
Enter an equation for a line through the points
\( (0,2) \) and \( (2,0) \).
\$BR
\$BR
\{ ans_rule(20) \}
END_TEXT

Main Text: We use AnswerFormatHelp("equations") to generate a link to an html help file with link text help (equations). The html help files are specifically designed to help students figure out the correct syntax for their answer, as well as common mistakes to avoid. We recommend placing a help link immediately after each answer blank in a problem, especially if there are different types of answers. Currently, help files are available for

• angles
• decimals
• exponents
• formulas
• fractions
• inequalities
• intervals
• logarithms
• limits
• numbers
• points
• syntax
• units
• vectors

It is possible to change the link text to help entering equations by including a second argument to the routine:

It is possible to provide a link to an external help file using \{ htmlLink("http://someplace.edu/help.html") \}. We do not recommend this as it requires external files be maintained and links not become broken (especially when the server changes or moves). Instead of using a link to an external help file, use the method described at the bottom of this page.

ENDDOCUMENT();

Instead of using a link to an external file, use the following:

<script type="text/javascript">
<!--
function openhelpCustom1() {
OpenWindow.document.write("<title>Help With Something</title>")
OpenWindow.document.write("<body bgcolor='#ffffff'>")
OpenWindow.document.write("<center><h2>Help With Something</h2></center>")
OpenWindow.document.write("<ul>")
OpenWindow.document.write("</ul>")
OpenWindow.document.write("</body>")
OpenWindow.document.write("</html>")
OpenWindow.document.close()
self.name="main"
if (window.focus) {OpenWindow.focus()}
return false;
}
-->
</script>

BEGIN_TEXT