Add Lecture 2
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@ -90,7 +90,14 @@ are referred to as *grid curves*.
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== Tangent vectors and normal vectors
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== Tangent vectors and normal vectors
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#proposition[
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#proposition[
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Consider the vector function $r(u,v) = chevron.l x(u,v), y(u,v), z(u,v) chevron.r$
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Consider the vector function $r(u,v) = chevron.l x(u,v), y(u,v), z(u,v) chevron.r$,
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then
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$
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r_u(u,v) = chevron.l x_u (u,v),y_u (u,v),z_u (u,v) chevron.r.
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$
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Similarly for $r_v (u,v)$
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#remark[
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#remark[
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@ -100,12 +107,17 @@ are referred to as *grid curves*.
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]
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#corollary[
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#corollary[
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The vectors $r_u (u_0, v_0)$ and $r_v (u_0, v_0)$ ar
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The vectors $r_u (u_0, v_0)$ and $r_v (u_0, v_0)$ are tangent to $S$ at the
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position $r(u_0, v_0)$.
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#definition[
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#definition[
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Let $P$ be a point in a surface $S$ that is not on the boundary of $S$. Then
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Let $P$ be a point in a surface $S$ that is not on the boundary of $S$. Then
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$S$ is called *smooth* at $P$ if $r_u "cross" r_v eq.not 0$
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$S$ is called *smooth* at $P$ if $r_u "cross" r_v eq.not 0$
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if $S$ is smooth at the point $P = r(u_0, v_0)$, then the *tangent plane*
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to $S$ at the point $P$ is the plane spanned by the tangent vectors $r_u (u_0, v_0)$
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and $r_v (u_0, v_0)$ through $P$.
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]
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#definition[
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#definition[
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@ -116,7 +128,7 @@ are referred to as *grid curves*.
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#theorem[
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#theorem[
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Suppose a parametric surface $S$, given by $r(u,v)$, is smooth ath the point
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Suppose a parametric surface $S$, given by $r(u,v)$, is smooth ath the point
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$r(u_0, v_0)$. Then the vector $n=r_u (u_0, v_0) times r_v (u_0, v_0)$ is a normal
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$r(u_0, v_0)$. Then the vector $n=r_u (u_0, v_0) times r_v (u_0, v_0)$ is a normal
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vector of $S$ at $r(u_0, v_0)$
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vector of $S$ at $r(u_0, v_0)$, provided it is nonzero.
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== Areas of parametric surfaces
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== Areas of parametric surfaces
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@ -135,3 +147,17 @@ are referred to as *grid curves*.
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"area"(S) = integral.double_S d S = attach(limits(integral.double),b:D) |r_u times r_v| d u d v
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"area"(S) = integral.double_S d S = attach(limits(integral.double),b:D) |r_u times r_v| d u d v
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$
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$
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== Lecture 2 - Surface Integrals
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*Orientable surfaces* are surfaces which have a "top" and a "bottom".
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#definition[
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The *surface integral* of $f$ over a surface $cal(S)$ in $RR^3$ is
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$
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attach(limits(integral.double), b: cal(S)) f d cal(S) = lim_(m arrow infinity) lim_(n arrow infinity) sum_(i=1)^(m) sum_(j=1)^n f(P_(i j)) Delta cal(S)_(i j)
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$
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A surface integral over a *closed surface* $cal(S)$ is denoted as $integral.surf_cal(S) f d cal(S)$.
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