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Show that the Points (3, 4), (−5, 16) and (5, 1) Are Collinear. - Mathematics

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Question

Show that the points (3, 4), (−5, 16) and (5, 1) are collinear.

Sum
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Solution

Let the given points be A(3, 4), B(−5, 16) and C(5, 1).
Now,
\[\overrightarrow{AB} = \left[ \left( - 5 \hat{i} + 16 \hat{j} \right) - \left( 3 \hat{i} + 4 \hat{j} \right) \right] = - 8 \hat{i} + 12 \hat{j}\]

\[\overrightarrow{AC} = \left[ \left( 5 \hat{i} + \hat{j} \right) - \left( 3 \hat{i} + 4 \hat{j} \right) \right] = 2 \hat{i} - 3 \hat{j}\]
Clearly,
\[\overrightarrow{AB} = - 4 \overrightarrow{AC}\]
Therefore,
\[\overrightarrow{AB}\] and \[\overrightarrow{AC}\] are parallel vectors. But, A is a common point of \[\overrightarrow{AB}\] and \[\overrightarrow{AC}\]
Hence, the given points (3, 4), (−5, 16) and (5, 1) are collinear.
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Chapter 23: Algebra of Vectors - Exercise 23.7 [Page 61]

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RD Sharma Mathematics [English] Class 12
Chapter 23 Algebra of Vectors
Exercise 23.7 | Q 9 | Page 61

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