Question

If a line has direction ratios 2, -1, -2, determine its direction cosines.

A 2/3, -1/3, -2/3 Correct Answer Incorrect Answer
B 2/5, -1/5, -2/5 Correct Answer Incorrect Answer
C 2, -1, -2 Correct Answer Incorrect Answer
D 1/2, -1/4, -1/2 Correct Answer Incorrect Answer

Solution

Directions cosines are: => 2/[√(22 + (-1)2 + (-2)2)], -1/[√(22 + (-1)2 + (-2)2)], -2/[√(22 + (-1)2 + (-2)2)] => 2/3, -1/3, -2/3

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