$A_{Dreieck}={\displaystyle \frac{1}{2}}\mathrm{\mid }\overrightarrow{PQ}\times \overrightarrow{PR}\mathrm{\mid }A\_\{Dreieck\}=\backslash dfrac\{1\}\{2\}|\backslash overrightarrow\{PQ\}\backslash times\backslash overrightarrow\{PR\}|$ ; $\overrightarrow{PQ}=\left(\begin{array}{c}2\\ -1\end{array}\right)\backslash overrightarrow\{PQ\}=\backslash begin\{pmatrix\}\; 2\; \backslash \backslash \; -1\; \backslash end\{pmatrix\}$; $\overrightarrow{PR}=\left(\begin{array}{c}4\\ 1\end{array}\right)\backslash overrightarrow\{PR\}=\backslash begin\{pmatrix\}\; 4\; \backslash \backslash \; 1\; \backslash end\{pmatrix\}$

FE

Nicht verlangt: Damit ergibt sich ein Flächeninhalt von $A_{\text{Dreieck}}={\displaystyle \frac{1}{2}}(2+4)\text{FE}=3\text{FE}A\_\backslash text\{Dreieck\}=\backslash dfrac\{1\}\{2\}(2+4)\backslash text\{FE\}=3\backslash text\{FE\}$.