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Question
In each of the following find the value of 'k', for which the points are collinear.
(7, -2), (5, 1), (3, -k)
Solution
For collinear points, area of triangle formed by them is zero.
Therefore, for points (7, -2) (5, 1), and (3, k), area = 0
`1/2 [7 { 1- k} + 5(k-(-2)) + 3{(-2) + 1}] = 0`
7 - 7k + 5k +10 -9 = 0
-2k + 8 = 0
k = 4
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