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NCERT Class 12 · Ch 4 Exercise 4.2 · Q2

NCERT Class 12 Maths · Chapter 4 Determinants · Exercise 4.2 Question 2

Show that (a,b+c), (b,c+a), (c,a+b) are collinear.
Illustration only: a=1, b=2, c=3; all points on x+y=6
Illustration only: a=1, b=2, c=3; all points on x+y=6

💡 Concept Hints

  1. Identify whether this needs determinant expansion, an inverse, or the absolute determinant formula for area.
  2. For a determinant use signed cofactors. For a system first check invertibility; for an area take half the absolute determinant.

✅ Step-by-Step Solution

Final Answer: The three points are collinear.
  1. Each point satisfies x+y=a+b+c, so all lie on the same straight line.
  2. Equivalently, in the area determinant C₁+C₂=(a+b+c)C₃. The columns are dependent, so the determinant and triangle area are zero.

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