TrigIdentities1

Trig Identities 1: Cleverly Redefining Functions

This PG code shows how to redefine a named function internally so that students must apply a trig identity and simplify their answer.

• Download file: File:TrigIdentities1.txt (change the file extension from txt to pg when you save it)
• File location in NPL: NationalProblemLibrary/FortLewis/Authoring/Templates/Trig/TrigIdentities.pg

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PG problem file	Explanation
Problem tagging data	Problem tagging:
DOCUMENT(); loadMacros( "PGstandard.pl", "MathObjects.pl", "AnswerFormatHelp.pl", "answerHints.pl", ); TEXT(beginproblem());	Initialization:
Context("Numeric"); Context()->functions->remove("tan"); package NewFunc; # this next line makes the function a # function from reals to reals our @ISA = qw(Parser::Function::numeric); sub tan { shift; my $x = shift; return CORE::exp($x*3.1415926535); } package main; # Make it work on formulas as well as numbers sub tan {Parser::Function->call('tan',@_)} # Add the new functions to the Context Context()->functions->add( tan => {class =>'NewFunc', TeX =>'\tan'}, );	Setup: We redefine the function whose name is tan(x) to take values exp(pi * x).
Context()->texStrings; BEGIN_TEXT Simplify the expression as much as possible. $BR $BR \( \tan(x) \cos(x) \) = \{ ans_rule(20) \} \{ AnswerFormatHelp("formulas") \} END_TEXT Context()->normalStrings;	Main Text:
$showPartialCorrectAnswers = 1; ANS(Formula("sin(x)")->cmp() ->withPostFilter(AnswerHints( Compute("tan(x)*cos(x)") => "No credit for entering what you were given.", )) );	Answer Evaluation:
Context()->texStrings; BEGIN_SOLUTION ${PAR}SOLUTION:${PAR} Solution explanation goes here. END_SOLUTION Context()->normalStrings; COMMENT('MathObject version.'); ENDDOCUMENT();	Solution:

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