Question

In reperul cartezian xOy se considera punctele A(4,2) B(1,1) C(-1,3). Calculati aria triunghiului ABC. Se poate sa fie scrisa asa cum se rezolva? Mersi :)

Answer 1

[tex]A_{\triangle ABC}= \frac{1}{2} \cdot |\triangle|~,unde\\ \triangle= \left|\begin{array}{ccc}x_A&y_A&1\\x_B&y_B&1\\x_C&y_C&1\end{array}\right| \\ \triangle= \left|\begin{array}{ccc}4&2&1\\1&1&1\\-1&3&1\end{array}\right| =-8\\ A_{\triangle ABC}= \frac{1}{2} \cdot |-8|=4[/tex]