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Annotation of /trunk/NationalProblemLibrary/WHFreeman/Rogawski_Calculus_Early_Transcendentals_Second_Edition/12_Vector_Geometry/12.2_Vectors_in_Three_Dimensions/12.2.27.pg

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1 : aubreyja 2584 ## DBsubject('Calculus')
2 :     ## DBchapter('Introduction to Differential Equations')
3 :     ## DBsection('Vectors in Three Dimensions')
4 :     ## KEYWORDS('calculus', 'parametric', 'vector', '3D', 'three dimensions')
5 :     ## TitleText1('Calculus: Early Transcendentals')
6 :     ## EditionText1('2')
7 :     ## AuthorText1('Rogawski')
8 :     ## Section1('12.2')
9 :     ## Problem1('27')
10 :     ## Author('Christopher Sira')
11 :     ## Institution('W.H.Freeman')
12 :    
13 :     DOCUMENT();
14 :     loadMacros("PG.pl","PGbasicmacros.pl","PGanswermacros.pl");
15 :     loadMacros("PGchoicemacros.pl");
16 :     loadMacros("Parser.pl");
17 :     loadMacros("freemanMacros.pl");
18 :     $context = Context("Vector");
19 :    
20 :     $a = Real(random(1,10,1));
21 :     $b = Real(random(1,10,1));
22 :     $c = Real(random(1,10,1));
23 :    
24 :     $v = Vector($a, $b, $c);
25 :     $w = -1 * $v;
26 :    
27 :     $len = sqrt($a**2 + $b**2 + $c**2);
28 :    
29 :     $ans = Vector($a / $len, $b / $len, $c / $len);
30 :    
31 :    
32 :     Context()->texStrings;
33 :     BEGIN_TEXT
34 :     \{ beginproblem() \}
35 :     \{ textbook_ref_exact("Rogawski ET 2e", "12.2","27") \}
36 :     $PAR
37 :     Find a unit vector \( \mathbf{u} \) in the direction opposite of \( $w \).
38 :     $PAR
39 :     \( \mathbf{u} \) = \{ans_rule()\}
40 :     END_TEXT
41 :     Context()->normalStrings;
42 :    
43 :     ANS($ans->cmp);
44 :    
45 :     Context()->texStrings;
46 :     SOLUTION(EV3(<<'END_SOLUTION'));
47 :     $PAR
48 :     $SOL
49 :     \( \mathbf{w} = $w \)
50 :     $PAR
51 :     \( \mathbf{v} = -1 * $w = $v \)
52 :     $PAR
53 :     \( \| \mathbf{v} \| = \sqrt{\mathbf{v} \cdotp \mathbf{v}} = \sqrt{$a * $a + $b * $b + $c * $c} = $len \).
54 :     $PAR
55 :     \( \mathbf{u} = \mathbf{e}_\mathbf{v} = \frac{1}{ \| \mathbf{v} \|} v = \left< \frac{$a}{$len},
56 :     \frac{$b}{$len}, \frac{$c}{$len} \right> = $ans \)
57 :     END_SOLUTION
58 :    
59 :     ENDDOCUMENT();
60 :    
61 :    

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