1.

Find the equations of a line passing through the point P(2,-1,3) and perpendicular to the lines `vec(r ) =(hat(i) + hat(j) -hat(k)) +lambda (2hat(i) -2hat(j) +hat(k))` and `vec( r) =(2hat(i) -hat(j) -3hat(k)) +mu (hat(i) +2hat(j) +2hat(k))`

Answer» The given lines are
`vec(r) =vec(a)_(1) +lambdavec(b)_(1) ......(i)" where " vec(a)_(1)=(hat(i) +hat(j) -hat(k)) " and " vec(b)_(1) =(2hat(i) -2hat(j) +hat(k))" and "`
`vec(r ) =vec(a)_(2) +lambda vec(b)_(2) .....(ii) " where "vec(a)_(2) =(2hat(i) -hat(j) -3hat(k)) " and " vec(b)_(2) =(hat(i) +2hat(j) +2hat(k))`
The required line is perpendicular to (i) as well as (ii) .
Also (i) is parallel to `vec(b)_(1) ` and (ii) is parallel to `vec(b)_(2)`
So the required line is perpendicular to both `vec(b)_(1) " and " vec_(b)_(2)`
Consequently this line must be parallel to `(vec(b)_(1)xx vec(b)_(2))`
Now , `(vec(b)_(1) xx vec(b)_(2)) =|{:(hat(i),,hat(j),,hat(k)),(2,,-2,,1),(1,,2,,2):}| =(-6hat(i) -3hat(j) +6hat(k))`
So we have to find the equation of a line passing through the point P(2,-1,3) and parallel to `(vec(b)_(1)xx vec(b)_(2))`
Hence the required equation is
`vec( r) =(2hat(i) -hat(j) +3hat(k)) + t (-6hat(i) -3hat(j) +6hat(k))
where t is an arbitrary constant.


Discussion

No Comment Found

Related InterviewSolutions