Question

Encontre a area do triângulo de vertices A(1,8),B(2,3) e C(-5,2)

Answer 1

$\left[\begin{array}{ccc}1&8&1\\2&3&1\\-5&2&1\end{array}\right] =A \\ \\ A = (3 + 4-40)-(-15+16+2) \\ \\ A = (-33)-(18) \\ \\ A = -33 + 18=-15 \\ \\ A = \frac{1}{2} |-15|=7,5$

Espero ter ajudado.