\begin{frame} \frametitle{The Area below a Curve} \begin{center} \scalebox{.9}{ \begin{tikzpicture}[default] \def\mfun{(4*(\x+\mfunshift) - 2.6*(\x+\mfunshift)^2 + .44*(\x+\mfunshift)^3)} {\def\diaborderx{.3cm} \def\diabordery{.3cm} \diagram[1]{-.5}{4}{-.4}{2}{1}} \diagramannotatez \def\mfunshift{0} \begin{scope}[ultra thick] \draw[cred] plot[smooth,domain=.5:3.5,samples=20] (\x,{\mfun}); \def\mwidth{3} \def\mstep{\mwidth/5} \def\mfunshift{0} \foreach \xx in {0,...,4} { \coordinate (height) at (0,0); \def\x{.5+ \xx*\mstep} \foreach \xxx in {0,0.01,...,1} { \gettikzxy{(height)} \def\mfunshift{\xxx*\mstep} \pgfmathparse{\mfun} \ifthenelse{\lengthtest{\pgfmathresult cm > \myy}}{ \coordinate (height) at (0,\pgfmathresult cm); }{} } \draw[thick,draw=cred!60!black,fill=cred,opacity=.5] ({\x},0) rectangle ($({\x+\mstep},0) + (height)$); } \node[anchor=north] at (.5,0) {$a$}; \node[anchor=north] at (3.5,0) {$b$}; \node at (2,-1.1) {upper sum $U_5$}; \end{scope} \end{tikzpicture}~\hspace{.5cm}~% \mpause[1]{% \begin{tikzpicture}[default] \def\mfun{(4*(\x+\mfunshift) - 2.6*(\x+\mfunshift)^2 + .44*(\x+\mfunshift)^3)} {\def\diaborderx{.3cm} \def\diabordery{.3cm} \diagram[1]{-.5}{4}{-.4}{2}{1}} \diagramannotatez \def\mfunshift{0} \begin{scope}[ultra thick] \draw[cred] plot[smooth,domain=.5:3.5,samples=20] (\x,{\mfun}); \def\mwidth{3} \def\mstep{\mwidth/5} \def\mfunshift{0} \foreach \xx in {0,...,4} { \coordinate (height) at (0,5); \def\x{.5+ \xx*\mstep} \foreach \xxx in {0,0.01,...,1} { \gettikzxy{(height)} \def\mfunshift{\xxx*\mstep} \pgfmathparse{\mfun} \ifthenelse{\lengthtest{\pgfmathresult cm < \myy}}{ \coordinate (height) at (0,\pgfmathresult cm); }{} } \draw[thick,draw=cred!60!black,fill=cred,opacity=.5] ({\x},0) rectangle ($({\x+\mstep},0) + (height)$); } \node[anchor=north] at (.5,0) {$a$}; \node[anchor=north] at (3.5,0) {$b$}; \node at (2,-1.1) {lower sum $D_5$}; \end{scope} \end{tikzpicture} } } \end{center}\vspace{-1ex} \begin{block}{} The \emph{upper sum} is \begin{malign} U_n = \Delta x\big(f(x_1) + f(x_2) + \ldots + f(x_n)\big) \end{malign}\vspace{-1ex} where $x_i$ is chosen from $I_i$ such that $f(x_i)$ is the maximum on $I_i$ \end{block} \pause \begin{block}{} The \emph{lower sum} is \begin{malign} D_n = \Delta x\big(f(x_1) + f(x_2) + \ldots + f(x_n)\big) \end{malign}\vspace{-1ex} where $x_i$ is chosen from $I_i$ such that $f(x_i)$ is the minimum on $I_i$ \end{block} \end{frame}