{VERSION 4 0 "IBM INTEL NT" "4.0" } {USTYLETAB {CSTYLE "Maple Input" -1 0 "Courier" 0 1 255 0 0 1 0 1 0 0 1 0 0 0 0 1 }{CSTYLE "2D Math" -1 2 "Times" 0 1 0 0 0 0 0 0 2 0 0 0 0 0 0 1 }{CSTYLE "2D Comment" 2 18 "" 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 1 } {CSTYLE "2D Output" 2 20 "" 0 1 0 0 255 1 0 0 0 0 0 0 0 0 0 1 } {CSTYLE "" -1 256 "" 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 }{CSTYLE "" -1 257 "" 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 }{CSTYLE "" -1 258 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 1 }{CSTYLE "" -1 259 "" 0 1 0 0 0 0 1 0 0 0 0 0 0 0 0 1 }{CSTYLE "" -1 260 "" 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 } {CSTYLE "" -1 261 "" 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 }{CSTYLE "" -1 262 "" 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 }{CSTYLE "" -1 263 "" 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 1 }{CSTYLE "" -1 264 "" 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 }{CSTYLE "" -1 265 "" 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 1 } {CSTYLE "" -1 266 "" 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 1 }{PSTYLE "Normal " -1 0 1 {CSTYLE "" -1 -1 "Times" 1 12 0 0 0 1 2 2 2 2 2 2 1 1 1 1 }1 1 0 0 0 0 1 0 1 0 2 2 0 1 }{PSTYLE "Heading 1" -1 3 1 {CSTYLE "" -1 -1 "Times" 1 18 0 0 0 1 2 1 2 2 2 2 1 1 1 1 }1 1 0 0 8 4 1 0 1 0 2 2 0 1 }{PSTYLE "Maple Output" -1 11 1 {CSTYLE "" -1 -1 "Times" 1 12 0 0 0 1 2 2 2 2 2 2 1 1 1 1 }3 3 0 0 0 0 1 0 1 0 2 2 0 1 }{PSTYLE "Maple P lot" -1 13 1 {CSTYLE "" -1 -1 "Times" 1 12 0 0 0 1 2 2 2 2 2 2 1 1 1 1 }3 1 0 0 0 0 1 0 1 0 2 2 0 1 }{PSTYLE "Title" -1 18 1 {CSTYLE "" -1 -1 "Times" 1 18 0 0 0 1 2 1 1 2 2 2 1 1 1 1 }3 1 0 0 12 12 1 0 1 0 2 2 19 1 }{PSTYLE "Normal" -1 256 1 {CSTYLE "" -1 -1 "Times" 1 12 0 0 0 1 2 2 2 2 2 2 1 1 1 1 }3 1 0 0 0 0 1 0 1 0 2 2 0 1 }{PSTYLE "Heading 2 " -1 257 1 {CSTYLE "" -1 -1 "Times" 1 14 0 0 0 1 2 1 2 2 2 2 1 1 1 1 } 3 1 0 0 8 2 1 0 1 0 2 2 0 1 }} {SECT 0 {EXCHG {PARA 18 "" 0 "" {TEXT -1 11 "Calculus II" }}{PARA 257 "" 0 "" {TEXT -1 34 "Lesson 26: Parametric Arc Length\n" }}}{EXCHG {PARA 0 "" 0 "" {TEXT -1 282 "In this worksheet, we will use the proce ss of integration to compute the lengths of plane parametric curves. \+ The same approach will find the lengths of 3-dimensional curves, but \+ we will not consider that extension. Suppose we are given a parametri c curve, described by equations " }{XPPEDIT 18 0 "x = f(t);" "6#/%\"xG -%\"fG6#%\"tG" }{TEXT -1 2 ", " }{XPPEDIT 18 0 "y = g(t);" "6#/%\"yG-% \"gG6#%\"tG" }{TEXT -1 7 ", t in " }{XPPEDIT 18 0 "[a, b];" "6#7$%\"aG %\"bG" }{TEXT -1 1 "." }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 35 "f \+ := t-> t^2 ; g := t-> t^3 - 3*t ;" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#> %\"fGR6#%\"tG6\"6$%)operatorG%&arrowGF(*$)9$\"\"#\"\"\"F(F(F(" }} {PARA 11 "" 1 "" {XPPMATH 20 "6#>%\"gGR6#%\"tG6\"6$%)operatorG%&arrowG F(,&*$)9$\"\"$\"\"\"F1*&F0F1F/F1!\"\"F(F(F(" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 28 "plot([f(t), g(t), t=-2..2]);" }}{PARA 13 "" 1 "" {GLPLOT2D 400 300 300 {PLOTDATA 2 "6%-%'CURVESG6$7^o7$$\"\"%\"\"!$!\"# F*7$$\"38*4j#*\\'G8R!#<$!3;DM!>&fm1=F07$$\"3&*GdQIK_FQF0$!3#o-8z:r*=;F 07$$\"3d))yO$>5Fu$F0$!3'Gzx4[`oV\"F07$$\"3A!e4#)QZ)eOF0$!3)4sYSy]-E\"F 07$$\"3xVC;(zv^^$F0$!3K(po71H*e'*!#=7$$\"3'*[e7aKF0$!3\"pWEh0W\"QRFG7$$\"3I_xvy7AoIF0$!3-P^xPq)\\>\"FG7 $$\"3U#*G?fOj>HF0$\"3wt+D%[9KP\"FG7$$\"3AdyQ%yLZx#F0$\"3espPO#zBv$FG7$ $\"3DBb'*)3%=MEF0$\"3VDPfFG7$$\"3eCFF07$$\"3UlK?Jn;z6F0$\"3Ux'=(>FBx>F 07$$\"3mq\"))\\%))R#***FG$\"3wx%elc*****>F07$$\"3ND5!QdEbL)FG$\"3!*\\# 3T.Zz(>F07$$\"3yo4Oxt$3)oFG$\"37?rUNLv<>F07$$\"3[Bt(zL,1o&FG$\"3V\"=0) Rt%H$=F07$$\"3%37I_u2IS%FG$\"3[a'R/h#\\)p\"F07$$\"39$[s$3d(yW$FG$\"3?; :'[&R5f:F07$$\"3W.`jPjd$[#FG$\"3[/<$>`%Hr8F07$$\"3'*4!*RKWoh6\"FG$\"3F.qiG`%Gj*FG7$$\"3CH$*>9#z`J'!#>$\"3 C8)RRNu#F]u$\"3SEePpx.t1BfFhu7$$\"3[xsBc\")3LuFh u$!3W:*[8J_+e#FG7$$\"3)*)*GqVMScEF]u$!35#=M_pZi%[FG7$$\"3SBo$=Oul/'F]u $!32+8a(*4DGsFG7$$\"3+&>/'3\")G*4\"FG$!3M(R^sdz@e*FG7$$\"3q1NSD.>D#pFG$!3A^2F07$$\"3:3Cjqg!*=%)FG$!3#)p#3 jdk,)>F07$$\"3))y\"p6+56'**FG$!3[hI-U'))***>F07$$\"3EMgH-EF07$$\"3K8jd&Q?gN\"F0$!3=;`a@hQ9>F07$$\"3k%GUH\"\\/k:F0$!3gmV#)45 $ez\"F07$$\"3qtR@7\\UyJ'3#)>a6\"F07$$\"3%*=tuAVIvBF0$!3a6AvEP#y i*FG7$$\"35^[pY)\\f\\#F0$!3A`HP_VFjzFG7$$\"3F[qlx&)*yj#F0$!3Sf`qi'46)e FG7$$\"3?XzA\")Gx$y#F0$!3#Gcn'G@n2OFG7$$\"3Jg-A7.dYE&*F]u7$$\"3I\"*y*>WrR?$F0$\"3uXvwkb,^O FG7$$\"3#3*)RIu/qN$F0$\"3M1>Urv3TlFG7$$\"3)zaASz?o]$F0$\"3)47P(\\L)4\\ *FG7$$\"3?')3\"\\D2*fOF0$\"3Ok^R>4Yi7F07$$\"3ktB^OT^VPF0$\"3aLoyuKcQ9F 07$$\"3`@xA@_1GQF0$\"3,g+#*3i9?;F07$$\"3KIp040c8RF0$\"3A[?Wo7F2=F07$F( $\"\"#F*-%'COLOURG6&%$RGBG$\"#5!\"\"$F*F*Ff`l-%+AXESLABELSG6$Q!6\"Fj`l -%%VIEWG6$%(DEFAULTGF_al" 1 2 0 1 10 0 2 9 1 4 2 1.000000 45.000000 45.000000 0 0 "Curve 1" }}}}{EXCHG {PARA 0 "" 0 "" {TEXT -1 36 "We par tition the parameter interval " }{XPPEDIT 18 0 "[a, b];" "6#7$%\"aG%\" bG" }{TEXT -1 6 " into " }{XPPEDIT 18 0 "n;" "6#%\"nG" }{TEXT -1 35 " \+ equal subintervals with endpoints " }{XPPEDIT 18 0 "t_0 = a;" "6#/%$t_ 0G%\"aG" }{TEXT -1 2 ", " }{XPPEDIT 18 0 "t_1;" "6#%$t_1G" }{TEXT -1 9 ", ... , \n" }{XPPEDIT 18 0 "t_n = b;" "6#/%$t_nG%\"bG" }{TEXT -1 196 " , and draw the piecewise-linear curve composed of line segments \+ joining the corresponding points on our original curve. It turns out \+ that, with some care, we can do this with the same procedure " }{TEXT 256 2 "pl" }{TEXT -1 77 " that we used earlier to compute arclengths o f graphs: we just have to apply " }{TEXT 257 2 "pl" }{TEXT -1 4 " to \+ " }{XPPEDIT 18 0 "f;" "6#%\"fG" }{TEXT -1 5 " and " }{XPPEDIT 18 0 "g; " "6#%\"gG" }{TEXT -1 12 " separately." }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 19 "pl := proc(f,a,b,n)" }}{PARA 0 "> " 0 "" {MPLTEXT 1 0 20 " local u,v,k;" }}{PARA 0 "> " 0 "" {MPLTEXT 1 0 38 " \+ k := 1 + floor(n*(x-a)/(b-a));" }}{PARA 0 "> " 0 "" {MPLTEXT 1 0 31 " u := a + (k-1)*(b-a)/n;" }}{PARA 0 "> " 0 "" {MPLTEXT 1 0 27 " v := a + k*(b-a)/n;" }}{PARA 0 "> " 0 "" {MPLTEXT 1 0 53 " unapply(f(u) + (f(v) - f(u))/(v-u)*(x-u), x);" }}{PARA 0 "> " 0 "" {MPLTEXT 1 0 15 " end proc:" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 20 "plf := pl(f,-2,2,6):" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 20 "plg := pl(g,-2,2,6):" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 66 "plot(\{[f(t),g(t),t=-2..2], [plf(t),plg(t),t=-2..2]\} , thickness=2);" }{TEXT -1 0 "" }}{PARA 13 "" 1 "" {GLPLOT2D 400 300 300 {PLOTDATA 2 "6'-%'CURVESG6$7^o7$$\"\"%\"\"!$!\"#F*7$$\"38*4j#*\\'G 8R!#<$!3;DM!>&fm1=F07$$\"3&*GdQIK_FQF0$!3#o-8z:r*=;F07$$\"3d))yO$>5Fu$ F0$!3'Gzx4[`oV\"F07$$\"3A!e4#)QZ)eOF0$!3)4sYSy]-E\"F07$$\"3xVC;(zv^^$F 0$!3K(po71H*e'*!#=7$$\"3'*[e7aKF0 $!3\"pWEh0W\"QRFG7$$\"3I_xvy7AoIF0$!3-P^xPq)\\>\"FG7$$\"3U#*G?fOj>HF0$ \"3wt+D%[9KP\"FG7$$\"3AdyQ%yLZx#F0$\"3espPO#zBv$FG7$$\"3DBb'*)3%=MEF0$ \"3VDPfFG7$$\"3eCFF07$$\"3UlK?Jn;z6F0$\"3Ux'=(>FBx>F07$$\"3mq\"))\\% ))R#***FG$\"3wx%elc*****>F07$$\"3ND5!QdEbL)FG$\"3!*\\#3T.Zz(>F07$$\"3y o4Oxt$3)oFG$\"37?rUNLv<>F07$$\"3[Bt(zL,1o&FG$\"3V\"=0)Rt%H$=F07$$\"3%3 7I_u2IS%FG$\"3[a'R/h#\\)p\"F07$$\"39$[s$3d(yW$FG$\"3?;:'[&R5f:F07$$\"3 W.`jPjd$[#FG$\"3[/<$>`%Hr8F07$$\"3'*4!*RKWoh6\"FG$\"3F.qiG`%Gj*FG7$$\"3CH$*>9#z`J'!#>$\"3C8)RRNu#F]u$\"3SEePpx.t1BfFhu7$$\"3[xsBc\")3LuFhu$!3W:*[8J_+e#F G7$$\"3)*)*GqVMScEF]u$!35#=M_pZi%[FG7$$\"3SBo$=Oul/'F]u$!32+8a(*4DGsFG 7$$\"3+&>/'3\")G*4\"FG$!3M(R^sdz@e*FG7$$\"3q1NSD.>D#pFG$!3A^2F07$$\"3:3Cjqg!*=%)FG$!3#)p#3jdk,)>F07$$\"3) )y\"p6+56'**FG$!3[hI-U'))***>F07$$\"3EMgH-EF07$$\"3K8 jd&Q?gN\"F0$!3=;`a@hQ9>F07$$\"3k%GUH\"\\/k:F0$!3gmV#)45$ez\"F07$$\"3qt R@7\\UyJ'3#)>a6\"F07$$\"3%*=tuAVIvBF0$!3a6AvEP#yi*FG7$$\"35^[pY )\\f\\#F0$!3A`HP_VFjzFG7$$\"3F[qlx&)*yj#F0$!3Sf`qi'46)eFG7$$\"3?XzA\") Gx$y#F0$!3#Gcn'G@n2OFG7$$\"3Jg-A7.dYE&*F]u7$$\"3I\"*y*>WrR?$F0$\"3uXvwkb,^OFG7$$\"3#3*)RIu /qN$F0$\"3M1>Urv3TlFG7$$\"3)zaASz?o]$F0$\"3)47P(\\L)4\\*FG7$$\"3?')3\" \\D2*fOF0$\"3Ok^R>4Yi7F07$$\"3ktB^OT^VPF0$\"3aLoyuKcQ9F07$$\"3`@xA@_1G QF0$\"3,g+#*3i9?;F07$$\"3KIp040c8RF0$\"3A[?Wo7F2=F07$F($\"\"#F*-%'COLO URG6&%$RGBG$\"#5!\"\"$F*F*Ff`l-F$6$7eoF'7$$\"3E*)))))QcoaQF0$!3'f=&=5K li@!=FG7$$\"3&pmmT!**QVFF0$\"3ELxx_cJY_F]u7 $$\"3aAAAZd$4g#F0$\"3yg.P&z#Q^GFG7$$\"3AMLL3D')oCF0$\"3xPbbI!z&3]FG7$$ \"3)\\WW%p#*yOBF0$\"3aK2ul_xlrFG7$$\"3ubbb!3N+?#F0$\"3!)*e#fF0$\"3]Y\"[1Y7VR\"F 07$$\"3y666O\"=/y\"F0$\"3)4&=NWqJD;F07$$\"3kWWW4`x%p\"F0$\"3aq.(y(3CM; F07$$\"3N666E')=5;F0$\"3sbb0Q,%*Q;F07$$\"3RWWWCI666JuX\"RFG$\"3uf#f#>oe+:F07$$\"3+MLL$=mBK$FG$\"3W66h.P dt7F07$$\"3qXWWW;;)z#FG$\"3#4Pq.jGE2\"F07$$\"3eKLL$=EIA#FG$\"3*>WW%p.g @&)FG7$$\"3[mmm;7Ov;FG$\"3`@AA(*z@AkFG7$$\"3kxxxx-$R5\"FG$\"3@\"[\"[JF tJUFG7$$\"3uXWWWHy\"z&F]u$\"3aPq.iM=?AFG7$$\"3Esmm;MqhHF]u$\"3xcb0V'>` 8\"FG7$$\"3/K*))))))QiJ\"Fhu$\"3c+wS2CeX]Fhu7$$\"3s)466OL!3GF]u$!39@fU )y7k2\"FG7$$\"3c)366h!pZdF]u$!3Xwxxx)=$R;FG$!3CV\"[\")pbSG'FG7$$\"3)))******fn.@#FG$!3; '******zvIZ)FG7$$\"3sjmmmt-pFFG$!3qabb!\\g91\"F07$$\"3?kmm;%f&4LFG$!3q ab0VWmo7F07$$\"3E(******4G(4RFG$!37*****\\5H()\\\"F07$$\"3#\\xxxAn$zTF G$!3JZ\"[1x!4-;F07$$\"3msxxx,8eWFG$!3$>&=&=nFOq\"F07$$\"3NTWWW@#=K&FG$ !3A[\"[JQH))p\"F07$$\"3/5666T^&='FG$!3aWWW%4JSp\"F07$$\"3GTWW%p!y]xFG$ !3s\"[\")*o^L&o\"F07$$\"3E56660.i%*FG$!3)ebbbAGen\"F07$$\"3*pxxFK=s5\" F0$!3]&=&oKH)om\"F07$$\"3o566wc_v7F0$!3'pmmT_Kvl\"F07$$\"3[xxxxo2S9F0$ !39T2u!z!R[;F07$$\"3z566OnM7;F0$!32cb0V-#)Q;F07$$\"3uxxF5\\I&p\"F0$!3L _=gb9@M;F07$$\"3kAAAAmey>F0$!3_.P?ETO (R\"F07$$\"3%=AAAnv81#F0$!3oq.PN(>k;\"F07$$\"3Pmm;z$*f,AF0$!3qYW%p!o(Q P*FG7$$\"3*366h3B=M#F0$!3O&=&=gib$3(FG7$$\"3CAAs4TnqCF0$!3S/P?T&*)*y\\ FG7$$\"37LLLL^_*f#F0$!3cCAAAGUuGFG7$$\"39AAAZH?ZFF0$!3`\"Qq.i=Ni%F]u7$ $\"39666h2)[*GF0$\"3[]\"[\")4>(\\>FG7$$\"3.LLLeb'p-$F0$\"3VUWW>T52TFG7 $$\"3Obbbb.0fJF0$\"3gO2uS\"*[kiFG7$$\"3K66h)H!))*H$F0$\"3q%[\")Ra6Zc)F G7$$\"3GnmmT-rSMF0$\"3%GAAZR$\\'3\"F07$$\"3EnmmmC]vNF0$\"3$**)))))GSl1 8F07$$\"3Dnmm\"p%H5PF0$\"3ecb0jY\"o_\"F07$$\"3iLL$eMZ^&QF0$\"3_yx_JtSj " 0 "" {MPLTEXT 1 0 217 "approxlen := proc(f,g,a,b,n)\n local l;\n \+ l := (b-a)/n;\n sum( sqrt( (f(a+j*l) - f(a+(j-1)* l))^2\n + (g(a+j*l) - g(a+(j-1)*l))^2 ), j=1..n);\n \+ end proc:" }}}{EXCHG {PARA 0 "" 0 "" {TEXT -1 11 "As always, " }{TEXT 258 5 "Maple" }{TEXT -1 114 " will evaluate the answer exact ly, including square roots, so it is convenient to ask for a decimal a pproximation." }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 29 "evalf(appr oxlen(f,g,-2,2,5));" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+**f&3X\"!\" )" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 30 "evalf(approxlen(f,g,-2 ,2,10));" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+91D/:!\")" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 30 "evalf(approxlen(f,g,-2,2,20));" }} {PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+95!o^\"!\")" }}}{EXCHG {PARA 0 "> \+ " 0 "" {MPLTEXT 1 0 30 "evalf(approxlen(f,g,-2,2,50));" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+l:E?:!\")" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 31 "evalf(approxlen(f,g,-2,2,100));" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+yhv?:!\")" }}}{EXCHG {PARA 0 "" 0 "" {TEXT -1 200 " We see a familiar pattern: as the number of subintervals increases, th e lengths of the piecewise-linear approximations approach a fixed valu e, which is obviously the true length of the original curve." }}} {EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}}{SECT 0 {PARA 3 "" 0 "" {TEXT -1 10 "Question 1" }}{EXCHG {PARA 0 "" 0 "" {TEXT -1 147 "Use pi ecewise-linear approximations to find the length of the loop of the cu rve above, accurate to within 0.01. (Hint: what are the two values of " }{XPPEDIT 18 0 "t;" "6#%\"tG" }{TEXT -1 35 " at the self-intersecti on point?)\n\n" }{TEXT 263 9 "Solution." }{TEXT -1 24 " The curve cro sses the " }{XPPEDIT 18 0 "x;" "6#%\"xG" }{TEXT -1 11 "-axis when " } {XPPEDIT 18 0 "t = -sqrt(3);" "6#/%\"tG,$-%%sqrtG6#\"\"$!\"\"" }{TEXT -1 16 " and again when " }{XPPEDIT 18 0 "t = sqrt(3);" "6#/%\"tG-%%sqr tG6#\"\"$" }{TEXT -1 18 ", both times when " }{XPPEDIT 18 0 "x = 3;" " 6#/%\"xG\"\"$" }{TEXT -1 54 ".\nThe length of the curve between these \+ two values of " }{XPPEDIT 18 0 "t;" "6#%\"tG" }{TEXT -1 27 " can be ap proximated using " }{TEXT 264 9 "approxlen" }{TEXT -1 1 ":" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 41 "evalf(approxlen(f,g,-sqrt(3),sqrt(3 ),5));" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+n7DI5!\")" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 42 "evalf(approxlen(f,g,-sqrt(3),sqrt(3 ),10));" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+\\a[h5!\")" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 42 "evalf(approxlen(f,g,-sqrt(3),sqrt(3 ),50));" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+N^-t5!\")" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 43 "evalf(approxlen(f,g,-sqrt(3),sqrt(3 ),100));" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+KeQt5!\")" }}}{EXCHG {PARA 0 "" 0 "" {TEXT -1 198 "Although we should probably try a larger number of subintervals to be sure that the second decimal place will \+ remain stable, we can probably assume that the length is 10.73, accura te to within 0.01." }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}}} {EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}}{SECT 0 {PARA 3 "" 0 "" {TEXT -1 10 "Question 2" }}{EXCHG {PARA 0 "" 0 "" {TEXT -1 21 "Plot th e polar curve " }{XPPEDIT 18 0 "r = theta;" "6#/%\"rG%&thetaG" }{TEXT -1 93 " . By writing it as a parametric curve, find the length of the portion of the curve between " }{XPPEDIT 18 0 "theta = 0;" "6#/%&thet aG\"\"!" }{TEXT -1 5 " and " }{XPPEDIT 18 0 "theta = 2*Pi;" "6#/%&thet aG*&\"\"#\"\"\"%#PiGF'" }{TEXT -1 3 ".\n\n" }{TEXT 265 9 "Solution." } {TEXT -1 44 " As a polar curve, our curve has equations " }{XPPEDIT 18 0 "x = theta*cos(theta);" "6#/%\"xG*&%&thetaG\"\"\"-%$cosG6#F&F'" } {TEXT -1 2 ", " }{XPPEDIT 18 0 "y = theta*sin(theta);" "6#/%\"yG*&%&th etaG\"\"\"-%$sinG6#F&F'" }{TEXT -1 1 "." }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 32 "f1 := theta-> theta*cos(theta) ;" }}{PARA 0 "> " 0 " " {MPLTEXT 1 0 0 "" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#>%#f1GR6#%&theta G6\"6$%)operatorG%&arrowGF(*&9$\"\"\"-%$cosG6#F-F.F(F(F(" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 32 "g1 := theta-> theta*sin(theta) ;" } }{PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}{PARA 11 "" 1 "" {XPPMATH 20 "6 #>%#g1GR6#%&thetaG6\"6$%)operatorG%&arrowGF(*&9$\"\"\"-%$sinG6#F-F.F(F (F(" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 44 "plot([f1(theta), g1( theta), theta=0..2*Pi]);" }}{PARA 13 "" 1 "" {GLPLOT2D 400 300 300 {PLOTDATA 2 "6%-%'CURVESG6$7en7$$\"\"!F)F(7$$\"3\"f&f3#*)G<$o!#>$\"3It C!fNUbo%!#?7$$\"3%zshZRJnN\"!#=$\"3[ewJkV#)p=F-7$$\"3*HW$>L2aF>F4$\"3f 0kA6_F4$\"3H% HWmze&QSF47$$\"3W(G@K$F4$\"3E/HfnR&GF\"F^o7$$\"3\"Q;;5`Y9$>F4$\"3 _#Q7/1CGU\"F^o7$$!3_+$Qd$)**GQ*!#@$\"3q4!yO:$Rr:F^o7$$!3-%po*)H(REBF4$ \"3u=#4$[qa\"p\"F^o7$$!3e,+4g>Gl[F4$\"37]^JqS1td(yoF^ o$\"3WE)**3:k0_\"F^o7$$!3'[!3Frr$oE#F^o$\"3@'oc=lJ$48F^o7$$!3q0DT%3&fN DF^o$\"3Q\\PJ0(oj0\"F^o7$$!3[d0*=#)eXy#F^o$\"3.MDB\\*H2T(F47$$!3!)>?jB $)=xHF^o$\"3E-8_\"*)\\#)3%F47$$!3\"*>?&fCw%QJF^o$\"34#p`l!GVL(*F07$$!3 KC+S%Q9qC$F^o$!30=S1<$3WU%F47$$!3K*GQLtooG$F^o$!3y3#[DT1Pg)F47$$!37;x> n\"QzE$F^o$!3t\\nAE#>!H8F^o7$$!3[*[K6TKo<$F^o$!3W`ga$yKB#=F^o7$$!3\\Yz KR9w9IF^o$!3??9u)*yW.BF^o7$$!3i&3K;mH$)y#F^o$!3%e')z9:lsv#F^o7$$!3E/s# )y+UdCF^o$!3::A@W;MNKF^o7$$!3Wf!QI6J54#F^o$!3Zb([JHz2j$F^o7$$!3\\_?on# H>j\"F^o$!3E*pneawe+%F^o7$$!3k'yg9'oXg6F^o$!3_?DU>/W%H%F^o7$$!3s$>wYE$ 3>fF4$!3>\"GtOG&[WXF^o7$$!3XzmLPK#)R9F-$!3wL@o\"e4$4ZF^o7$$\"3YqIMIx`M iF4$!3P6v>x-@,[F^o7$$\"3=#zURC\\+F\"F^o$!3]A!*G.&od![F^o7$$\"3'fZ%*G5 \"ee>F^o$!31]EKeW[:ZF^o7$$\"3+AQAhF\"*>EF^o$!3W,Z')G-$Q`%F^o7$$\"3a%>( R*=&\\!G$F^o$!3a.qk&oK5D%F^o7$$\"3B!Q5$eW)e!RF^o$!3_p@ujivuQF^o7$$\"3% RZg$*yP%zTF^o$!3afl#y,m1n$F^o7$$\"3xHF5/(\\CW%F^o$!3sbJmL(4vW$F^o7$$\" 3$3$[\"))zK#HZF^o$!3wr;19o**oJF^o7$$\"3yl(*HU!4&)*\\F^o$!3)e'Hn0F5nGF^ o7$$\"3EIK7em)HA&F^o$!3OX.w/x#\\=KcF^o$!3[w+:\\GoG>F^o7$$\"3Dqb#\\#=w6eF^o$!3eA)[XHB#o:F^ o7$$\"3=n`*ogR='fF^o$!3N9W[N9x37F^o7$$\"3Idki$et%*3'F^o$!3)31[w'*4aO)F 47$$\"3S:*)eS;X+iF^o$!3,ZWvco-RUF47$$\"3?+++3`=$G'F^o$\"3qF=n%R6[:&!#E -%'COLOURG6&%$RGBG$\"#5!\"\"F(F(-%+AXESLABELSG6$Q!6\"F\\^l-%%VIEWG6$%( DEFAULTGFa^l" 1 2 0 1 10 0 2 9 1 4 2 1.000000 45.000000 45.000000 0 0 "Curve 1" }}}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 34 "evalf(approxle n(f1,g1,0,2*Pi,50));" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+ " 0 "" {MPLTEXT 1 0 35 "evalf(approxlen(f1,g1,0 ,2*Pi,100));" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+!3!=D@!\")" }}} {EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 35 "evalf(approxlen(f1,g1,0,2*Pi ,500));" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+R9hD@!\")" }}}{EXCHG {PARA 0 "" 0 "" {TEXT -1 58 "The length of the curve appears to be app roximately 21.25." }}}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 0 "" }}} {EXCHG {PARA 0 "" 0 "" {TEXT -1 18 "With the power of " }{TEXT 259 5 " Maple" }{TEXT -1 26 ", the numerical procedure " }{TEXT 260 9 "approxl en" }{TEXT -1 425 " is all we need to find arclengths as accurately as we want. Very often a numerical procedure of this type is the only p ractical way of finding arclength, but it is possible to write down an integral which gives the exact length of the curve. (In practice, th e integral will have to be evaluated numerically for most curves of in terest.) As explained in class, an argument with the Mean Value Theor em leads to the integral" }}}{EXCHG {PARA 256 "" 0 "" {XPPEDIT 18 0 "I nt(sqrt(diff(f,t)^2+diff(g,t)^2),t = a .. b);" "6#-%$IntG6$-%%sqrtG6#, &*$-%%diffG6$%\"fG%\"tG\"\"#\"\"\"*$-F,6$%\"gGF/F0F1/F/;%\"aG%\"bG" } {TEXT -1 2 " ." }}}{EXCHG {PARA 0 "" 0 "" {TEXT -1 113 "The following \+ procedure returns this integral. Since many arclength integrals canno t be evaluated synbolically, " }{TEXT 261 9 "arclength" }{TEXT -1 39 " returns the integral unevaluated; use " }{TEXT 262 5 "evalf" }{TEXT -1 45 " to get a decimal approximation to its value." }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 117 "arclength := proc(f,g,a,b) \n \+ Int(sqrt(diff(f(t),t)^2 + diff(g(t),t)^2), t=a..b);\n \+ end proc:" }}}{EXCHG {PARA 0 "" 0 "" {TEXT -1 153 "For the example we \+ have been using, we can confirm that the integral formula agrees with \+ the arclength we found from the piecewise-linear approximations:" }}} {EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 35 "f := t-> t^2 ; g := t-> t^3 \+ - 3*t ;" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#>%\"fGR6#%\"tG6\"6$%)operat orG%&arrowGF(*$)9$\"\"#\"\"\"F(F(F(" }}{PARA 11 "" 1 "" {XPPMATH 20 "6 #>%\"gGR6#%\"tG6\"6$%)operatorG%&arrowGF(,&*$)9$\"\"$\"\"\"F1*&F0F1F/F 1!\"\"F(F(F(" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 27 "evalf(arcle ngth(f,g,-2,2));" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+j5#4_\"!\")" } }}{SECT 0 {PARA 3 "" 0 "" {TEXT -1 10 "Question 3" }}{EXCHG {PARA 0 " " 0 "" {TEXT -1 131 "Confirm that the integral formula agrees with the results you obtained with piecewise-linear approximations in Question s 1 and 2.\n\n" }{TEXT 266 9 "Solution." }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 39 "evalf(arclength(f,g,-sqrt(3),sqrt(3)));" }}{PARA 11 " " 1 "" {XPPMATH 20 "6#$\"+og]t5!\")" }}}{EXCHG {PARA 0 "> " 0 "" {MPLTEXT 1 0 31 "evalf(arclength(f1,g1,0,2*Pi));" }}{PARA 11 "" 1 "" {XPPMATH 20 "6#$\"+:%Hc7#!\")" }}}{EXCHG {PARA 0 "" 0 "" {TEXT -1 224 "These two values agree with the approximations obtained in Questions \+ 1 and 2, at least in the first few decimal places. If we were to use \+ more subintervals in Questions 1 and 2, we would of course get better \+ approximations." }}}}}{MARK "8 1 0" 0 }{VIEWOPTS 1 1 0 1 1 1803 1 1 1 1 }{PAGENUMBERS 0 1 2 33 1 1 }