हिंदी

Find the length and the foot of perpendicular from the point (1,32,2) to the plane 2x – 2y + 4z + 5 = 0.

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प्रश्न

Find the length and the foot of perpendicular from the point `(1, 3/2, 2)` to the plane 2x – 2y + 4z + 5 = 0.

योग
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उत्तर

Given plane is 2x – 2y + 4z + 5 = 0 and point `(1, 3/2, 2)`

The direction ratios of the normal to the plane are 2, –2, 4

So, the equation of the line passing through `(1, 3/2, 2)` and direction ratios are equal to the direction ratios of the normal to the plane i.e. 2, –2, 4 is

`(x - 1)/2 = (y - 3/2)/(-2) = (z - 2)/4 = lambda`

Now, any point in the plane is 2λ + 1, –2λ + `3/2`, 4λ + 2

Since, the point lies in the plane, then

2(2λ + 1) – 2(–2λ + `3/2`) + 4(4λ + 2) + 5 = 0

4λ + 2 + 4λ – 3 + 16λ + 8 + 5 = 0

24λ + 12 = 0λ = `1/2`

So, the coordinates of the point in the plane are

`2(-1/2) + 1, -2(-1/2) + 3/2, 4(-1/2) + 2 = 0, 5/2, 0`

Thus, the foot of the perpendicular is (0, 5/2, 0) and the required length

= `sqrt((1 - 0)^2 + (3/2 - 5/2)^2 + (2 - 0)^2)`

= `sqrt(1 + 1 + 4)`

= `sqrt(6)` units

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अध्याय 12: Introduction to Three Dimensional Geometry - Exercise [पृष्ठ २३६]

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एनसीईआरटी एक्झांप्लर Mathematics Exemplar [English] Class 11
अध्याय 12 Introduction to Three Dimensional Geometry
Exercise | Q 18 | पृष्ठ २३६

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