HSC Science (Electronics) 12th Board ExamMaharashtra State Board
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# Solution - Find the Shortest Distance Between the Lines r=(4i-j)+λ(i+2j-3k) and r=(i-j+2k)+μ(i+4j-5k) - HSC Science (Electronics) 12th Board Exam - Mathematics and Statistics

#### Question

Find the shortest distance between the lines

bar r = (4 hat i - hat j) + lambda(hat i + 2 hat j - 3 hat k)

and

bar r = (hat i - hat j + 2 hat k) + mu(hat i + 4 hat j -5 hat k)

where λ and μ are parameters

#### Solution

We know that the shortest distance between the lines

bar r=bara_1+lambdabarb_1 and barr=bara_2+mubarb_2

Given equation of lines are

bar r=(4hati-hatj)+lambda(hati+2hatj-3hatk) and barr=(hati-hatj+2hatk)+mu(hati+4hatj-5hatk)

therefore bara_2-bara_1=(hati-hatj+2hatk)-(4hati-hatj)=-3hati+2hatk

barb_1xxbarb_2=|[hati,hatj,hatk],[1,2,-3],[1,4,-5]|

=hati(-10+12)-hatj(-5+3)+hatk(4-2)

=2hati+2hatj+2hatk

(bara_2-bara_1).(barb_1xxbarb_2)=(-3hati+2hatk).(2hati+2hatj+2hatk)=-3xx2+0xx2+2xx2=-2

|barb_1xxbarb_2|=sqrt(4+4+4)=2sqrt3

Shortest distance =

d=|-2/(2sqrt3)|=|-1/sqrt3|=1/sqrt3 units.

Is there an error in this question or solution?

#### APPEARS IN

2015-2016 (March) (with solutions)
Question 2.1.3 | 3 marks

#### Reference Material

Solution for question: Find the Shortest Distance Between the Lines r=(4i-j)+λ(i+2j-3k) and r=(i-j+2k)+μ(i+4j-5k) concept: Shortest Distance Between Two Lines. For the courses HSC Science (Electronics), HSC Science (Computer Science), HSC Arts, HSC Science (General)
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