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Write the Ratio in Which Yz-plane Divides the Segment Joining P (−2, 5, 9) and Q (3, −2, 4).

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Question

Write the ratio in which YZ-plane divides the segment joining P (−2, 5, 9) and Q (3, −2, 4).

Sum
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Solution

\[ \text{ Let the YZ - plane divide the line segment joining points } P\left( - 2, 5, 9 \right) \text { and Q } \left( 3, - 2, 4 \right) \text{ in the ratio k: 1 } . \]

\[ \text{ Using the section formula, the coordinates of the point of intersection are given by }\]

\[\left( \frac{k\left( 3 \right) - 2}{k + 1}, \frac{k\left( - 2 \right) + 5}{k + 1}, \frac{k\left( 4 \right) + 9}{k + 1} \right)\]

\[ \text{ On the YZ - plane, the X - coordinate of any point is zero } . \]

\[ \therefore \frac{k\left( 3 \right) - 2}{k + 1} = 0\]

\[ \Rightarrow 3k - 2 = 0\]

\[ \Rightarrow k = \frac{2}{3}\]

\[ \text{ Thus, the YZ - plane divides the line segment formed by joining the given points in the ratio 2: 3 internally  } . \]

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Chapter 26: Direction Cosines and Direction Ratios - Very Short Answers [Page 24]

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R.D. Sharma Mathematics Volume 1 and 2 [English] Class 12
Chapter 26 Direction Cosines and Direction Ratios
Very Short Answers | Q 7 | Page 24

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