Q. 3
Mark (√) against the correct answer in each of the following:
If A(1, 2, -3) and B(-1, -2, 1) are the end points of a vector 
then the direction cosines of 
are
A. -2, -4, 4
B. 
C. 
D. none of these
Answer :
Given - A(1, 2, -3) and B(-1, -2, 1) are the end points of a vector 
Tip – If P(a1,b1,c1) and Q(a2,b2,c2) be two points then the vector 
is represented by 
Hence, 
Formula to be used – The direction cosines of a vector 
is given by 
.
Hence, the direction cosines of the vector 
is given by
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