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 #3
avatar+2489 
+3

Trapezoid and Trapezium are in use in both American (US) and European English; however, the formal meanings are reversed.  

 

Geometry.   Trapezoid   (Greek)

  1. a quadrilateral plane figure having two parallel and two nonparallel sides.
  2. British. trapezium (def. 1b).

Source: https://www.dictionary.com/browse/trapezoid

 

GeometryTrapezium  (Latain)

      1.   (in Euclidean geometry) any rectilinear quadrilateral plane figure not a parallelogram.

      2.  a quadrilateral plane figure of which no two sides are parallel.

     3.  British. trapezoid (def. 1a).

Source: https://www.dictionary.com/browse/trapezium

 

Wikipedia offers a more detailed history for the etymology of these words

https://en.wikipedia.org/wiki/Trapezoid

 

GA

 

--. .-

Oct 18, 2020
 #1
avatar+118653 
+2

I do not think that it exists.

Let

A = \(\begin{pmatrix} a\;b\;c\\ d\;e\;f\\ h\;i\;j\\ \end{pmatrix}\)

 

\(\begin{pmatrix} a\;b\;c\\ d\;e\;f\\ h\;i\;j\\ \end{pmatrix} \cdot \begin{pmatrix} 1\\0\\0 \end{pmatrix}= \begin{pmatrix} a\\d\\h \end{pmatrix}= \begin{pmatrix} -3\\4\\0 \end{pmatrix}\\ so\\ a=-3\qquad d=4\qquad h=0\)

 

 

\(\begin{pmatrix} -3\;b\;c\\ 4\;e\;f\\ 0\;i\;j\\ \end{pmatrix} \cdot  \begin{pmatrix} 0\\1\\1 \end{pmatrix}= \begin{pmatrix} b+c\\e+f\\i+j \end{pmatrix}= \begin{pmatrix} 1\\2\\3 \end{pmatrix}\\ so\\ c=1-b \qquad f=2-e\qquad j=3-i\)

 

 

\(\begin{pmatrix} -3\;\;b\;\;1-b\\ 4\;\;e\;\;2-e\\ 0\;i\;\;\;3-i\\ \end{pmatrix} \cdot  \begin{pmatrix} 1\\1\\1 \end{pmatrix}= \begin{pmatrix} -3+1\\4+2\\0+3 \end{pmatrix}= \begin{pmatrix} -2\\6\\3 \end{pmatrix}\ne \begin{pmatrix} 3\\2\\1 \end{pmatrix}\\ \)

 

 

 

 

LaTex:

\text{\begin{pmatrix}
a\;b\;c\\
d\;e\;f\\
h\;i\;j\\
\end{pmatrix}

 

\begin{pmatrix}
a\;b\;c\\
d\;e\;f\\
h\;i\;j\\
\end{pmatrix}
\cdot 
\begin{pmatrix}
1\\0\\0
\end{pmatrix}=
\begin{pmatrix}
a\\d\\h
\end{pmatrix}=
\begin{pmatrix}
-3\\4\\0
\end{pmatrix}\\
so\\ a=-3\qquad b=4\qquad c=0

 

\begin{pmatrix}
-3\;b\;c\\
4\;e\;f\\
0\;i\;j\\
\end{pmatrix}
\cdot 
\begin{pmatrix}
0\\1\\1
\end{pmatrix}=
\begin{pmatrix}
b+c\\e+f\\i+j
\end{pmatrix}=
\begin{pmatrix}
1\\2\\3
\end{pmatrix}\\
so\\ c=1-b \qquad f=2-e\qquad j=3-i

 

\begin{pmatrix}
-3\;\;b\;\;1-b\\
4\;\;e\;\;2-e\\
0\;i\;\;\;3-i\\
\end{pmatrix}
\cdot 
\begin{pmatrix}
1\\1\\1
\end{pmatrix}=
\begin{pmatrix}
-3+1\\4+2\\0+3
\end{pmatrix}=
\begin{pmatrix}
-2\\6\\3
\end{pmatrix}\ne
\begin{pmatrix}
3\\2\\1
\end{pmatrix}\\}

 

Oct 18, 2020
 #2
avatar+407 
0
Oct 18, 2020

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