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Explain solution for RD Sharma maths class 12 chapter 26 Direction Cosines and Direction Ratios exercise 26.1 question 4 maths textbook solution

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Answer: The points are collinear

Hint: Direction ratios of parallel line are proportional.

Given: Points A(2, 3, -4), B(1, -2, 3) and C(3, 8, -11)

Solution:

Direction ratio of AB are = (1-2, -2-3, 3-(-4))

                              = (-1, -5, -7)

Direction ratio of BC are = (3-1, 8-(-2), -11-3)

                              = (2, 10, -14)

Comparing direction ratio of AB and BC

              \frac{-1}{2}=\frac{-5}{10},\frac{7}{-14}

Hence, both are proportional and B is the common point in parallel lines.

Therefore, A, B and C are collinear points.

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