What is The area of a triangle whose vertices are j (-2,1), k (4,3) and l (-2,-5)?

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Answer 1 · 2018-04-23T17:00:35

$18$ $18$ .

Recall that, the Area $Delta$ of $DeltaABC$ with vertices

$A(x_1,y_1), B(x_2,y_2) and C(x_3,y_3)$ is given by,

$Delta=1/2|D|$ , where,

$D=|(x_1,y_1,1),(x_2,y_2,1),(x_3,y_3,1)|$ ,

In our case, $D=|(-2,1,1),(4,3,1),(-2,-5,1)|$ ,

$=-2{3-(-5)}-1{4-(-2)}+1{-20-(-6)}$ ,

$=-16-6-14$ ,

$=-36$ .

$rArr Delta=18$ .