Thanks for help
## DBsubject(Trigonometry)
## DBchapter(Trigonometric functions)
## DBsection(Sine & cosine functions - definitions, graphs, & properties)
## Institution(Univeristy of Utah)
## Author(Utah ww group)
## MLT(Amp_per_shift_formula)
## Level(2)
## TitleText1('Precalculus')
## AuthorText1('Ron Larson and Robert Hostetler')
## EditionText1('7')
## Section1('.')
## Problem1('')
## KEYWORDS('algebra')
DOCUMENT(); # This should be the first executable line in the problem.
loadMacros(
"PGstandard.pl", # Standard macros for PG language
"MathObjects.pl",
"PGcourse.pl", # Customization file for the course
"PGchoicemacros.pl",
"PGanswermacros.pl",
"AnswerFormatHelp.pl",
);
TEXT(beginproblem());
Context("Numeric");
Context()->variables->add(t=>'Real');
$showPartialCorrectAnswers = 1;
$a=random(2,1,9); # amplitude
$b=random(100,50,900); # frequency
$c=non_zero_random(-3.13,0.1,3.13); # phase shift
$d=non_zero_random(-9,1,9); # offset
$pi=2.0*acos(0.0);
Context()->texStrings;
BEGIN_TEXT
Knowledge of sinusoidal functions
$BR
Let
\[f(x)=$a \cos(2 \pi $b t + $c) + $d.\]
The amplitude of this function is
\{ ans_rule(12) \},
$BR
its period is
\{ ans_rule(12) \},
$BR
its phase shift is
\{ ans_rule(12) \},
$BR
and its offset is
\{ ans_rule(12) \},
END_TEXT
ANS(num_cmp( $a));
ANS(num_cmp( 1/$b));
ANS(num_cmp( $c));
ANS(num_cmp( $d));
ENDDOCUMENT(); # This should be the last executable line in the problem.