I need to make these two images in TIKZ, the image on the left I got, it's ready. Now I need to remove the solid below this function, I'm not sure where to begin. I want to show with the image of the left the integral under the surface and in the image of the right which volume is being calculated.
Removing the solid is as simple as removing the code that produces it from this code.
\documentclass[tikz,border=3.14mm]{standalone}
\usepackage{tikz-3dplot}
\begin{document}
\tdplotsetmaincoords{60}{110}
\begin{tikzpicture}[tdplot_main_coords,>=stealth,declare function={%
pfft(\x)=pi+0.3*sin(deg(\x));}]
\draw[->] (0,0,0) coordinate (O) -- (5,0,0) coordinate(X) node[pos=1.1]{$x$};
\draw[->] (O) -- (0,5,0) node[pos=1.1]{$y$};
\draw[->] (O) -- (0,0,5) node[pos=1.1]{$z$};
\path[opacity=0.3,left color=blue,right color=blue,middle color=blue!20,shading
angle=72]
plot[variable=\x,domain=0:1.1*pi,smooth] (3,\x,{pfft(2*\x)}) --
plot[variable=\x,domain=1.1*pi:0,smooth] (0,\x,{pfft(2*\x)}) -- cycle;
\path[opacity=0.3,left color=blue,right color=blue,middle color=blue!20,shading
angle=72]
plot[variable=\x,domain=1.1*pi:2.2*pi,smooth] (3,\x,{pfft(2*\x)}) --
plot[variable=\x,domain=2.2*pi:1.1*pi,smooth] (0,\x,{pfft(2*\x)}) -- cycle;
\draw plot[variable=\x,domain=0:2.2*pi,smooth] (3,\x,{pfft(2*\x)}) --
plot[variable=\x,domain=2.2*pi:0,smooth] (0,\x,{pfft(2*\x)}) -- cycle;
\end{tikzpicture}
\end{document}
