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Write direction ratios of the vector a = i + j − 2k and hence calculate its direction
cosines?

santhosh , 9 Years ago
Grade 12
anser 1 Answers
KUNCHAM SAMPATH

Last Activity: 9 Years ago

Note that direction ratios a, b, c of a vector r = x i + yj + zk are just the respective
components c, y and z of the vector. So, for the given vector, we have a = 1, b=1,
c= –2. Further, if l, m and n the direction cosines of the given vector, then
a
1
b
1
c
2
=
,m =
=
,n =
=−
|r|
|r|
|r|
6
6
6
l=
as | r |= 6
Thus, the direction cosines are
2 ⎞
⎛ 1 1
,
,−

⎟.
6⎠
⎝ 6 6
 

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