The mid-point P of the line segment joining the points A (- 10, 4) and B (- 2, 0) lies on the line segment joining the points C (- 9,-4) and D (- 4, y). Find the ratio in which P divides CD. Also, find the value of y.

Here given points are A (- 10, 4) and B (- 2, 0)and the points of other segment line are C (- 9,-4) and D (- 4, y)


Let the point of intersection between AB and CD be P



By midpoint formula.


x = , y =


For midpoint of AB,


e = , d = …(say)


e = -6 and d = 2 …(1)


By section formula,


x = , y =


For point P on CD, where ratio is m:n,


-6 = and 2 =


Solving for m and n,


-6 =


-6(m + n) = -4m -9n


6m + 6n = 4m + 9n


2m = 3n


=


Ratio is 3:2


Now solving for y, where m = 3 and n = 2,


2 =


3y -8 = 10


3y = 18


y = 6


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