## WeBWorK Problems

### Where does SampleProblem2 get its correct answers?

by Murray Eisenberg -
Number of replies: 0
In SampleProblem2 from
http://webwork.maa.org/wiki/SampleProblem2
where does Part 1 get its correct answer that's fed into the ANS function for this part?

The initialization for Part 1 is:
Context()->variables->add(t=>'Real');
$a = random(2,9,1);$func = Formula("cos($a t)");$funcDeriv = $func->D('t');$m = $funcDeriv->eval(t=>2);$y0 = $func->eval(t=>2);$line = Formula("$m (t - 2) +$y0");

Find the equation of the line tangent to $$f(t) = func$$ at $$t=2$$.
$$y =$$ \{ ans_rule(35) \} 
ANS( $funcDeriv->cmp() );  As I understand it, the correct answer here with which the student's answer is compared turns out to be the derivative at t = 2 and NOT the right-hand side of the equation y = ... for the tangent line there. Shouldn't the answer be checked, instead, by the following? ANS($line->cmp() );