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Per NCERT §3.5, a vector A in 3D has components along three orthogonal axes that satisfy which identity (with direction cosines cos α, cos β, cos γ)?
Atan α + tan β + tan γ = 0
Bcos²α + cos²β + cos²γ = 1
Ccos α + cos β + cos γ = 1
Dcos²α + cos²β + cos²γ = 0
Answer & Solution
Correct answer: B. cos²α + cos²β + cos²γ = 1
NCERT §3.5: A_x² + A_y² + A_z² = A² gives cos²α + cos²β + cos²γ = 1.
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