Question

Qual área do triângulo de vértices A(-5,1), B(1,3) e C(4,-2)?​

Answer 1

M= |-5 1 1|

|1 3 1|

|4 -2 1|

Det M= -5(3+2)-1(1-4)+1(-2-12)

Det M=-25+3-14=-36

$A=\frac{1}{2}. |Det M| \\ A=\frac{1}{2}.|-36| \\ A=\frac{1}{2}.36$

$A=18 u.a$