# If a Line Has the Direction Ratios −18, 12, −4, Then What Are Its Direction Cosines? - Mathematics

Sum

If a line has the direction ratios −18, 12, −4, then what are its direction cosines?

#### Solution

The direction ratios of the lines are -18, 12, -4

Direction cosines of the lines are

-18/sqrt(18^2 + 12^2+ 4^2), 12/sqrt(18^2 + 12^2 + (-4)^2), - 4/sqrt(18^2 + 12^2 + 4^2)

Hence, direction cosine of line are -9/11 , 6/11, -2/11

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#### APPEARS IN

NCERT Class 12 Maths
Chapter 11 Three Dimensional Geometry
Q 3 | Page 467