If the direction cosines of a line are connected by relation l+2m+n=0, 2l-2m+3n=0, then what is the value of l^2+m^2-n^2?

NDA 2024 Mathematics question

If the direction cosines of a line are connected by relation , , then what is the value of ?

Answer: (B)

By cross-multiplication, , i.e. . Since

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Question ID VK-029828