Question

Observe o triângulo ABC qual é a área desse triângulo​

Answer 1

Olá,

Para descobrir a área, vamos usar as coordenadas dos vértices.

A (1, 3), B (4, -1) e C (4, 2)

$D=\left[\begin{array}{ccc}x_A&y_A&1\\x_B&y_B&1\\x_C&y_C&1\end{array}\right]\\\\\\\ D= \left[\begin{array}{ccc}1&3&1\\4&-1&1\\4&2&1\end{array}\right] \\\\\\ D=\left[\begin{array}{ccc}1&3&1\\4&-1&1\\4&2&1\end{array}\right]\left\begin{array}{ccc}1&3\\4&-1\\4&2\end{array}\right\\\\\\ D=DP-DS\\\\ D=(1\cdot(-1)\cdot1+3\cdot1\cdot4+1\cdot4\cdot2)-(3\cdot4\cdot1+1\cdot1\cdot2+1\cdot(-1)\cdot4)\\\\D=(-1+12+8)-(12+2+(-4))\\\\D=19 -10\\\\D=9\\\\\\A=\dfrac{|D|}{2}=\dfrac{9}{2}=\boxed{\boxed{4,5u^2}}$

Espero ter ajudado.

Bons estudos! :)