Question

Find the value of k if the points (8,1) and (k,-4) and (2,5) are collinear

Answer 1

Answer:

1/2 x [X1 (Y2 - Y3 ) + X2(Y3 - Y1) + X3(Y1 - Y2)] = 0

1/2 [8(-4 - 5) + k(5-1) + 2(1- -4)] = 0

{(8 x -9) + 4k + (2 x 5)} = 0 x 2 = 0

-72 + 4k + 10 =0

4k -62 = 0

k = 62/4 =31/2 = 15.5

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