Define direction cosines of a directed line.

The direction cosines of a directed line can be defined as cosine values of the angles made by the directed line with the x-axis, y-axis and z-axis respectively.


Explanation:


Consider a directed line , in the three dimensional space.


If α, β and γ be the angles made by the directed line with the x-axis, y-axis and z-axis respectively.



In the above figure, the direction cosines of line OA are:


Cos α = cosine of the angle between x-axis (OX) and the directed line.


Cos β = cosine of the angle between y-axis (OY) and the directed line.


Cos γ = cosine of the angle between z-axis (OZ) and the directed line.


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