Explicație pas cu pas:
[tex]\left|\begin{array}{ccc}4&3&1\\5&3&1\\2&5&1\end{array}\right| = 12 + 6 + 25 - 6 - 20 - 15 = 2[/tex]
[tex]A_{ABC}=\frac{1}{2} \times |\left|\begin{array}{ccc}4&3&1\\5&3&1\\2&5&1\end{array}\right|| = \frac{1}{2} \times |2| = \frac{2}{2} = 1[/tex]