minor fixes

Author: thomasWeise

text/main/classes/inheritance/inheritance.tex

@@ -135,7 +135,7 @@
 The class \pythonil{Triangle} is implemented in very much the same fashion.
 This time, we need to store all three corner points (and also return all of them in the \pythonil{points}~method implementation).
 There also is no better way for computing the perimeter than what \pythonil{Polygon} already provides, so we this time do not override~\pythonil{perimeter}.
-The area computation is implemented using the formula~$A=x_1(y2-y3)+x_2(y_3-y_1)+x_3(y_1-y_2)$ you probably remember from high school maths.
+The area computation is implemented using the formula~$A=x_1(y_2-y_3)+x_2(y_3-y_1)+x_3(y_1-y_2)$ you probably remember from high school maths.
 
 Notice that both subclasses of \pythonil{Polygon} offer some \pglspl{doctest} in the \pglspl{docstring}.
 While I needed to keep the \pglspl{docstring} short to be able to fit the listings on pages, these \pglspl{doctest} still are instructive for the user.%
@@ -161,7 +161,7 @@
 You could define this as a class with (at least) two methods \pythonil{draw_line} and \pythonil{draw_rectangle}.
 We could then go an implement these methods in a class in such a way that constructs an SVG graphic~\cite{DDGLMSWFJJ2011SVGSSE} in memory.
 Another implementation could instead construct an Adobe~PDF~\cite{A2024WDPM,A2008P3DMPDFP1P1} graphic.
-While doing this would be more complex and exceed the space that we can reasonable use for an example in this book, the principle approach would not be very different from what you have already learned here.%
+While doing this would be more complex and exceed the space that we can reasonable use for an example in this book, the principle of the approach would not be very different from what you have already learned here.%
 \endhsection%
 %
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text/main/controlFlow/exceptions/exceptions.tex

@@ -533,7 +533,7 @@
 
 We open the file \textil{example.txt} for writing.
 To do so, we call the built-in function~\pythonilIdx{open}.
-We pass in the filename~\pythonIdx{"example.txt"} as first parameter.
+We pass in the filename~\textil{"example.txt"} as first parameter.
 The second parameter, \pythonil{mode}\pythonIdx{open!mode}, is set to~\pythonil{"w"}, which means \inQuotes{open for writing.}
 The parameter \pythonil{encoding}\pythonIdx{open!encoding} is set to~\pythonil{"UTF-8"}\pythonIdx{UTF-8}, which defines that the text should be translated to binary form when it is stored in the file via the usual \pgls{utf8}~encoding~\cite{Y2003UATFOI1,ISOIEC106462020ITUCCSU}.
 This is of no importance here and we will discuss this eventually later in the book.