Engineering
Mathematics
theorem in space
Section Formulae and Centres of a Triangle
Distance from a Plane
Question

The ratio in which the join of (1, –2,4) and (4, 2, –1) divided by the XY plane is

1 : 4

1 : 3

4 : 1

3 : 1

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Solution

Let P be the point where the line joining the given two points (1, –2, 4) and (4, 2, –1) intersects the X – Y plane in m : n ratio. We are to find m : n.

Now the co-ordinate of the point P be (4m+nm+n,2m2nm+n,m+4nm+n).
As the point P lies on the X – Y plane
m+4nm+n=0
or, –m + 4n = 0
or, mn=41
or, m : n = 4 : 1