Integration picture with tikz [closed]

how can I reproduce this picture with tikz please. I tried to export it from GeoGebra, but it doesn't satisfy me.

\begin{tikzpicture}

% Axes
\draw[->] (-1.5,0) -- (2.5,0);
\draw[->] (0,-1) -- (0,2);

% Axes labels
\node[below] at (2.5,0) {$x$};
\node[left] at (0,2) {$y$};

% Fonction
\draw[line width=1pt] plot[domain=-1.5:2.5,samples=50] function{x^2};

% Points
\draw[red] (-1.5,2.25) -- (-1.5,0);
\draw[red] (1.5,2.25) -- (1.5,0);
\draw[red] (0,0) -- (0,2);

% Texte
\node[red] at (-1.5,2.25) {$a$};
\node[red] at (1.5,2.25) {$a$};
\node[red] at (0,2) {$D$};

% Unité
\draw[black,dashed] (-0.75,-0.2) -- (-0.75,0.2);
\node[black] at (-0.75,0) {1};

\end{tikzpicture}

• In the pgfmanual tikz.dev look for: \draw, \node, to[out=..,in=..] for a start. Once you have code to show, please post it here, so we can help. Also, there are similar drawings here. Commented Dec 7, 2023 at 19:37
• where can I find similar pictures ? Can you put the link here please ? Commented Dec 7, 2023 at 20:25
• You could look at this tutorial in the TikZ manual to get a basic knowledge about how to draw things with TikZ. For the curve, you could use the plot operator, but you could also just draw some curve if the curve doesn't need to be exact. Commented Dec 7, 2023 at 21:10
• @Fractal, please. use. this. checklist. and stop posting fragments today. tex.meta.stackexchange.com/a/10137/245790 Thank you Commented Dec 7, 2023 at 21:22

The key is, to forget about "integration" and perceive more graphical elements, pathes at best (the Tikz-way).