Question

área do triângulo, cujo vértices são (1,2),(3,4)e(4,-1) ,e igual a:

Answer 1

Da Geometria Analítica:

$A=\frac{1}{2}\left|\left|\begin{array}{ccc}1&2&1\\3&4&1\\4&-1&1\end{array}\right| \right| \\ \\ A=\frac{1}{2} \times|4+8-3-16+1-6|\\ \\ A=\frac{1}{2} \times |-12|\\ \\ A=\frac{1}{2}\times 12\\ \\ A=6$