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The x-coordinate of a point on the line joining the points Q(2, 2, 1) and R(5, 1, –2) is 4. Find its z-coordinate. - Mathematics

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Question

The x-coordinate of a point on the line joining the points Q(2, 2, 1) and R(5, 1, –2) is 4. Find its z-coordinate.

Sum
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Solution

Let the point P divide QR in the ratio λ : 1, then the co-ordinate of P are

`((5lambda + 2)/(lambda + 1), (lambda + 2)/(lambda + 1), (-2lambda + 1)/(lambda + 1))`

But x– coordinate of P is 4.

Therefore, `(5lambda + 2)/(lambda + 1)` = 4

⇒ λ = 2

Hence, the z-coordinate of P is `(-2lambda + 1)/(lambda + 1)` = –1.

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Chapter 11: Three Dimensional Geometry - Solved Examples [Page 225]

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NCERT Exemplar Mathematics [English] Class 12
Chapter 11 Three Dimensional Geometry
Solved Examples | Q 4 | Page 225

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