Question:

The points with position vectors \(60\hat{i}+3\hat{j}, 40\hat{i}-8\hat{j}, a\hat{i}-52\hat{j}\) are collinear if

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Equal slopes ⇒ collinear points.
Updated On: Apr 30, 2026
  • \(a=-10\)
  • \(a=40\)
  • \(a=20\)
  • \(a=10\)
  • \(a=-40\)
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The Correct Option is C

Solution and Explanation

Concept: Points are collinear if slopes are equal.

Step 1:
Write coordinates. \[ A(60,3), B(40,-8), C(a,-52) \]

Step 2:
Slope AB. \[ \frac{-8-3}{40-60} = \frac{-11}{-20} = \frac{11}{20} \]

Step 3:
Slope BC. \[ \frac{-52+8}{a-40} = \frac{-44}{a-40} \]

Step 4:
Equate slopes. \[ \frac{11}{20} = \frac{-44}{a-40} \] \[ 11(a-40) = -880 \] \[ a-40 = -80 \] \[ a = -40 \]
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