help to create these environments (tcolorbox or tikz)?

Question

I'm trying to create these environments but without much success ... I wonder if it will be better to create it with tikz or if it is easier to customize the title of a tcolorbox and rotate it a bit ?

\documentclass{book}
\usepackage[T1]{fontenc}
\usepackage{tikz,tikzpagenodes}
\usepackage[most]{tcolorbox}
\usetikzlibrary{calc}
\usetikzlibrary{intersections, patterns}
\tcbuselibrary{skins}
\usepackage{lipsum}
\usepackage{xcolor,etoolbox}


\definecolor{lightblue}{RGB}{199,232,250}
\definecolor{darkblue}{RGB}{59,134,215}

\begin{document}



\begin{tikzpicture}[overlay,remember picture]
    % container 
    \draw[fill=darkblue,draw=none] (0,0) -- ++(5cm,0) -- ++(0,1cm)
    arc (0:90:0.5) -- ++(-4.5cm,0) -- cycle;
    % Horizontal line 
    \draw[darkblue, line width=2pt] (0,0) -- (\textwidth,0);
    % title of container 
    \node[scale=1.2] at (0.2cm,0.2cm)  {\textcolor{white}{Environment
        Title }};
  \end{tikzpicture}


\end{document}

%%% Local Variables: 
%%% mode: latex
%%% TeX-master: t
%%% End: 

Answer 1

I propose an other answer quite similar to the one given by @Ignasi but not exactly the same:

(reedited with the improvement proposed by @TeXnician related to the vertical shift of the top line)

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{tikz}
\usepackage[most]{tcolorbox}
\usetikzlibrary{calc}
\tcbuselibrary{skins}
\usepackage{xcolor}


\definecolor{titleboxcolor}{RGB}{199,232,250}
\definecolor{darkblue}{RGB}{59,134,215}

\newcommand{\titlepath}{
  \fill[titleboxcolor]
  (title.south east)
  --(title.east)coordinate(A)
  to[curve to,out=90,in=0]($(A)+(-5mm,5mm)$)
      --($(title.north west)+(5mm,0mm)$)coordinate(B)
to[curve to,out=180,in=90]($(B)+(-5mm,-5mm)$)coordinate(C)
      --($(C)+(0mm,-5mm)$)
      to[curve to,out=90,in=180]($(title.south west)+(+5mm,0mm)$)coordinate(F)
      --cycle;
      \draw[titleboxcolor,ultra thick]
      ([yshift=.5\pgflinewidth]title.south east)--
      ([yshift=.5\pgflinewidth]title.south-|interior.east);
    }


\newtcolorbox{myenvironment}{
  enhanced,
  frame empty,
  title=Exercice résolu,
  colback=white,
  coltitle=red,
  attach boxed title to top left={xshift=-5mm},
  boxed title style={empty},
  underlay boxed title=\titlepath

}

\begin{document}

\begin{myenvironment}
  Soit \(f\) une fonction définie sur ...
\end{myenvironment}



\end{document}

Answer 2

Something to start working:

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[most]{tcolorbox}
\usepackage{lipsum}

\makeatletter
\newtcolorbox{mybox}[2][]{
        enhanced, 
        breakable,
        sharp corners,
        rounded corners=northwest,
        colback=white,
        colframe=orange!80!black,
        fonttitle=\bfseries\large\sffamily,
        frame hidden,
        title=#2,
        attach boxed title to top left,
        boxed title size=standard,
        boxed title style={%
                empty,
                rounded corners=north, 
                boxrule=0pt,
                bottom=0pt,
        },
          underlay boxed title={%
                \filldraw[rounded corners=\kvtcb@arc, orange!80!black, line width=.5mm]
                    (title.south east)--++(93:\tcboxedtitleheight)--++(183:\tcboxedtitlewidth)--++(-87:\tcboxedtitleheight)|-cycle;
                \draw[tcbcolframe, line width=.5mm] (title.south)|-(frame.north east);
                },
        #1
    }
\makeatother

\begin{document}
\begin{mybox}{Exercice résolu}
\lipsum[2]
\end{mybox}

\end{document}

Note Previous code has been updated for compatibility with tcolorbox v4.20. If you're using previous versions, rename colors with form tcbcol... to older form tcbcol@....