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Find the equation of the line joining A( 1,3) and B (0,0) using determinants and find k if D(k, 0) is a point such that area of triangle ABD is 3sq units.

Answer» Area of a triangle is given by,
`Ar = 1/2|[x_1,y_1,1],[x_2,y_2,1],[x_3,y_3,1]|`
For the given triangle,
`3 = 1/2|[1,3,1],[0,0,1],[k,0,1]|`
`=>|[1,3,1],[0,0,1],[k,0,1]| = 6`
`=>[1(0-0)-3(0-k)+1(0-0)] = +-6`
`=>-3k = 6 and -3k = -6`
`=>k = -2 and k = 2`
So, required value of `k` is `+-2`.


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