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Class 12 Three Dimensional Geometry · Conceptual Answer1 Marksdirection_cosines

Class 12 Maths · Three Dimensional Geometry · Conceptual Answer #30

A directed line makes angles 90° and 60° with the positive x- and y-axes. Find its possible angle with the positive z-axis.

✅ Step-by-Step Solution

Final Answer: 30° or 150°.
  1. cos²γ=1−0−1/4=3/4; hence cos γ=±√3/2.
  2. 30° or 150°.

📋 CBSE Stepwise Marking Scheme

  • [0.5 marks] cos²γ=1−0−1/4=3/4; hence cos γ=±√3/2.
  • [0.5 marks] 30° or 150°.

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