1 % Requires the following code at some point after `\begin{document}`:
3 % usepackage("wtk_cmmds");
5 % This allows macros like `\vect{}` to be used in 3D graphics. See
6 % https://sourceforge.net/tracker/?func=detail&atid=685683&aid=3155798&group_id=120000
10 A rectangular parallelpiped has dimensions $a$, $b$, and $c$ as shown
11 in Figure 3.63. \Part{a} Obtain a vector expression for the face
12 diagonal vector $\vect{R}_1$. \Part{b} What is the magnitude of this
13 vector? \Part{c} Notice that $\vect{R}_1$, $c\khat$, and $\vect{R}_2$
14 make a right triangle. Obtain a vector expression for the body
15 diagonal vector $\vect{R}_2$.
17 \begin{asy}[inline=true,attach=false]
21 currentprojection = perspective(10cm,4cm,5cm);
29 xaxis3(Label("$x$"), 0, 1.5a);
30 yaxis3(Label("$y$"), 0, 1.5b);
31 zaxis3(Label("$z$"), 0, 1.5c);
34 draw(xscale3(a)*yscale3(b)*zscale3(c)*unitcube, surfacepen=opacity(0.2), meshpen=currentpen);
37 draw((0, 0, 1.3c) -- (a, 0, 1.3c), Arrows3);
38 label(Label("$a$", (0, 0, 1)), (a/2, 0, 1.3c));
39 draw((0, 0, 1.3c) -- (0, b, 1.3c), Arrows3);
40 label(Label("$b$", (0, 0, 1)), (0, b/2, 1.3c));
41 draw((0, 1.3b, 0) -- (0, 1.3b, c), Arrows3);
42 label(Label("$c$", (0, 1, 0)), (0, 1.3b, c/2));
45 draw(surface((0,0,0)--(a,b,0)--(a,b,c)--(0,0,c)--cycle), yellow+opacity(0.3), nolight, meshpen=dashed);
47 //Vector A = Vector((0,0,0), (a,b,0));
48 draw((0,0,0) -- (a,b,0), Arrow3);
49 label(Label("$\vect{R}_1$", (1,1,0)), position=(a,b,0));
50 draw((0,0,0) -- (a,b,c), Arrow3);
51 label(Label("$\vect{R}_2$", (0,1,-1)), (a,b,c));
59 \vect{R}_1 = \ans{a\ihat + b\jhat}
64 |\vect{R_1}| = \sqrt{\vect{R}_{1,x}^2 + \vect{R}_{1,y}^2}
65 = \ans{\sqrt{a^2 + b^2}}
70 \vect{R}_2 = \vect{R}_1 + c\khat
71 = \ans{a\ihat + b\jhat + c\khat}