If the points A(a, –11), B(5, b), C(2, 15) and D(1, 1) are the vertices of a parallelogram ABCD, find the values of a and b. -Maths 9th

1 Answer

Answer :

Let the x-axis divide the line joining the points (–2, 5) and (1, –9) in the ratio k : 1. Let the point of division on x-axis is P Then,\(x\) = \(rac{k-2}{k+1}\), y = \(rac{-9k+5}{k+1}\)As this is a point on the x–axis, y = 0∴ \(rac{-9k+5}{k+1}\) = 0 ⇒ 9k = 5 ⇒ k = \(rac{5}{9}\)k being positive, the division is internal. ∴ x-axis divides the given line internally in the ratio 5 : 9.

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