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Find the shortest distance between lines ` -> r=6 hat i+2 hat j+ hat k+lambda( hat i-2 hat j+2 hat k)`and ` -> r=-4 hat i- hat k+mu(3 hat i-2 hat j-2 hat k)`. |
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Answer» Comparing the given equations with the standard equations `vec( r)=vec( a)_(1) =lambda vec( b)_(1) " and " vec( r) =vec(a)_(2) +lambda vec( b)_(2) ` we have `vec(a)_(1) =(6hat(i) +2hat(j) +2hat(k)) ,vec(b)_(1) =(hat(i) -2hat(j) +2hat(k))` `vec(a)_(2) =(-4hat(i) -hat(k)) " and " vec( b)_(2) =(3hat(i) -2hat(j) -2hat(k))` `:. (vec(a)_(2) -vec(a)_(1))=(-4hat(i) -hat(k)) -(6hat(i) +2hat(j)+2hat(k))=(-10hat(i) -2hat(j) -2hat(k))` and `(vec(b)_(1) xx vec(b)_(2)) =|{:(hat(i),,hat(j),,hat(k)),(1,,-2,,2),(3,,-2,,-2):}|=(4+4)hat(i)-(-2-6) hat(j) +(-2+6)hat(k)` ` =(8hat(i)+8hat(j) +4hat(k))` `:. |vec(b)_(1) xx vec(b)_(2)|=sqrt(8^(2) +8^(2)+4^(2))=sqrt(64+64 +16)` `:. SD =|((vec(a_(2)-vec(a)_(1))).(vec(b)_(1)xxvec(b)_(2)))/(|vec(b)_(1)xxvec(b)_(2)|)|` `=|((-10hat(i)-2hat(j)-3hat(k)).(8hat(i)+8hat(j)+4hat(k)))/(12)| =|(-80 -16 -12)/(12)|` `=|(-108)/(12)| =|-9| =9` units |
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