Q12 of 18 Page 1103

Find the angle between the two lines whose direction cosines are:

and


Let


R1 =


And R2 =


R1.R2 = |R1||R2|cos


Here, as R1 and R2 are the unit vectors with a direction given by the direction cosines hence, |R1| and |R2| are 1.


So, cos = R1.R2 / 1


ð cos


ð =


The angle between the lines is


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