Vectorr

Find vector which is orthogonal to vector 3i+2j+6k and is coplanar with 2i+j+k and i+j-k

4 Answers

62
Lokesh Verma ·

k(2i+j+k)+m(i+j-k) as the vector coplanar to the two vectors.. then use the condition that it is orthogonal with vector 2i+2j+6k

by taking dot product..

so (2k+m).2+(k+m).2+(k-m).6=0
so (2k+m)+(k+m)+(k-m)3=0

so 6k-m=0

so m=6k

so you have a lot of vectors given by

(8i+7j-5k)k for all values of k

(please see that there are 2 k's in the expression i have written .. one is a parameter.. another is the vector along z direction)

24
eureka123 ·

a=3i+2j+6k
b=2i+j+k
c=i+j-k

Actually explaianation was given
r=ax(bxc)

plz explain this

106
Asish Mahapatra ·

That is possible

See bxc is perpendicular to the plane containing b and c.
So its cross product with another vector makes the new vector perpendicular to bxc and hence lie in the same plane of b and c

Similarly ax(bxc) is perpendicular to a

Hence the answer

62
Lokesh Verma ·

any vector perpendicular to bxc will lie in the plane containing both b and c...

also r is perpendicular (orthogonal) to a and (bxc) by the answer..

:)

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