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Question
Find the direction cosines of a vector whose direction ratios are
0, 0, 7
Solution
The given direction ratios are a = 0, b = 0, c = 7
If a, b, c are the direction ratios of a vector then the direction cosines of the vector are
l = `"b"/sqrt("a"^2 + "b"^2 + "c"^2)`
m = `"b"/sqrt("a"^2 + "b"^2 + "c"^2)`
c = `"c"/sqrt("a"^2 + "b"^2 + "c"^2)`
∴ The required direction cosines of the water are
= `0/sqrt(0^2 + 0^2 + 7), 0/sqrt(0^2 + 0^2 + 7^2), 7/sqrt(0^2 + 0^2 + 7^2)`
= `0/7, 0/7, 7/7`
= (0, 0, 1)
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