\newcommand \nal {\par\smallskip\noindent}
\newcommand \tr {\par\noindent$\triangleright$\ }
\newcommand \dv {differentiaalvergelijking}
\newcommand \rico {richtingco"effici"ent}
\newenvironment{Kern} [1] {\addtocounter{Kern}{1}\noindent\mbox{\large \bf Kern
\arabic{Kern}\ \ #1}
      \par\bigskip}{\newpage}
\newenvironment{deelkern} [1] {\indent{\bf #1} \dotfill\nal} {\nal}
\newenvironment{kleurvlak} {\nal\hrulefill\par\noindent}                          
{\par\nopagebreak[4]\noindent\hrulefill\nal}
\newenvironment{voorbeeld} {\par\medskip\noindent
      {\bf Voorbeeld\par\medskip\noindent}}{}			
\newenvironment{aanpak} [1] {\par\medskip\noindent
      {\bf Aanpak\par\medskip\noindent} #1
      \begin{list} {\tr}{}}
      {\end{list}}     
\newenvironment{opgave} {\stepcounter{opgave} 
      \begin{list} {\ifnum\value{onderdeel}=1
                       {\bf\arabic{opgave}\ \alph{onderdeel}}
		     \else
		       {\bf \alph{onderdeel}}
		     \fi
		    } 
		    {\usecounter{onderdeel}}
      }
      {\end{list}}
\newenvironment{opgavetekst}[1] {\stepcounter{opgave} 
       \pagebreak[1]\nal{\bf \arabic{opgave}} \hfill \begin {minipage} [t] {4.5in} 
                               #1 
                              \end {minipage}
			        }
      {}
\newenvironment{opgaveplus} [1] {\stepcounter{opgave} 
       \pagebreak[1]\nal{\bf \arabic{opgave}} \hfill \begin {minipage} [t] {4.5in} 
                               #1 
                              \end {minipage}  
       \begin{list} {{\bf\alph{onderdeel}}} {\usecounter {onderdeel}}}
      {\end{list}}

\newcommand \bop {\begin {opgave}}
\newcommand \eop {\end {opgave}}
\newcommand \bopp {\begin {opgaveplus}}
\newcommand \eopp {\end {opgaveplus}}
\newcommand \bopt {\begin {opgavetekst}}
\newcommand \eopt {\end {opgavetekst}}
\newcommand \bdk {\begin {deelkern}}
\newcommand \edk {\end {deelkern}}
\newcommand \bke {\begin {Kern}}
\newcommand \eke {\end {Kern}}
\newcommand \bkv {\begin {kleurvlak}}
\newcommand \ekv {\end {kleurvlak}}
\newcommand \bvb {\par\medskip\noindent\begin {voorbeeld}}
\newcommand \evb {\end {voorbeeld}}
\newcommand \bap {\begin {aanpak}}
\newcommand \eap {\end {aanpak}}
\newcommand \opm [1] {\stepcounter{opmerking} {\bf Opmerking \arabic{opmerking}} 
                     {\it #1}}
\newcommand \btn [1] {\framebox{\sc #1}}
\newcounter {Kern} [chapter]
\newcounter {opgave} [chapter]
\newcounter {onderdeel}
\newcounter {opmerking}
