Question

B) Calcule a área do triângulo de vértices A (2,4), B (1,8) e C (-2,5).



É urgente pessoal

Answer 1

$P=\begin{vmatrix}2&4&1\\1&8&1\\-2&5&1\end{vmatrix}$

$\mathsf{det~P=2(8-5)-4(1+2)+1(5+16)}\\\mathsf{det~P=6-12+21}\\\mathsf{det~P=15}$

$\mathsf{A=\dfrac{1}{2}.|det~P|}\\\mathsf{A=\dfrac{1}{2}.15}$

$\large\boxed{\boxed{\boxed{\boxed{\mathsf{A=\dfrac{15}{2}~u.a}}}}}$