A) \[1/3\]
B) \[2/3\]
C) \[-2/3\]
D) \[0\]
Correct Answer: D
Solution :
Given, position vector of A and B are, \[OA=4i-3j-k\] \[OB=5i-5j+k\] \[\Rightarrow \] \[AB=OB-OA\] \[=(5i-5j+k)-(4i-3j-k)\] \[=(i-2j)\] Position vector of z-axis is let \[OC=(0i+0j+k)\] Given, angle between AB and OC (z-axis) is r. \[\Rightarrow \] \[\cos \gamma =\frac{AB.OC}{|AB||OC|}=\frac{(i-2j).k}{\sqrt{1+4}.\sqrt{1}}=\frac{0}{\sqrt{5}}=0\] \[\Rightarrow \] \[\cos \,\gamma =0\]You need to login to perform this action.
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