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If a line makes angles α, β, γ with the positive directions of the coordinate axes, then the value of sin2α + sin2β + sin2γ is ______.

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Question

If a line makes angles α, β, γ with the positive directions of the coordinate axes, then the value of sin2α + sin2β + sin2γ is ______.

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Solution

If a line makes angles α, β, γ with the positive directions of the coordinate axes, then the value of sin2α + sin2β + sin2γ is 2.

Explanation:

Note that sin2α + sin2β + sin2γ = (1 – cos2α) + (1 – cos2β) + (1 – cos2γ)

= 3 – (cos2α + cos2β + cos2γ)

= 2.

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Chapter 11: Three Dimensional Geometry - Solved Examples [Page 234]

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NCERT Exemplar Mathematics Exemplar [English] Class 12
Chapter 11 Three Dimensional Geometry
Solved Examples | Q 21 | Page 234

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