Question

Calcule a area do triangulo de vértices A(1,5) B(4,7) C(-1,6)



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Answer 1

$\large\boxed{\begin{array}{l}\sf M=\begin{vmatrix}\sf1&\sf5&\sf1\\\sf4&\sf7&\sf1\\\sf-1&\sf6&\sf1\end{vmatrix}\\\sf det~M=1\cdot(7-6)-5\cdot(4+1)+1\cdot(24+7)\\\sf det~M=1-25+31\\\sf det~M=7\\\sf A=\dfrac{|det~M|}{2}\\\\\sf A=\dfrac{7}{2}\\\\\sf A=3,5~u\cdot a\end{array}}$