JEE Main · 2026 · 23 Jan 2026 · Shift 1 · Three Dimensional Geometry

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Let the direction cosines of two lines satisfy the equations: and .

Then the cosine of the acute angle between these lines is:
  1. (A)
  2. (B)
  3. (C)
  4. (D)✓ Correct

Answer: (D)

Solution

From , we get .

Substituting into :







Factoring: .

Case 1: , so . Direction ratios: or .

Case 2: , so . Direction ratios: or .

Cosine of angle: .

JEE Main · 2026 · 23 Jan 2026 · Shift 1 · Single correct option

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