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The length of the perpendicular drawn from the point (2, 1, 4) to the plane containing the lines `r=(hati+hatj)+lambda(hati+2hatj-hatk)" and "r=(hati+hatj)+mu(-hati+hatj-2hatk)` isA. 3B. `(1)/(3)`C. `sqrt(3)`D. `(1)/(sqrt(3))` |
Answer» Correct Answer - C Length of the perpendicular drawn from point `(x_(1), y_(1), z_(1))` to the plane `ax+by+cz+d=0`is `d_(1)=(|ax_(1)+by_(1)+cz_(1)+d|)/(sqrt(a^(2)+b^(2)+c ^(2)))` Given line vectors `r=(hati+hatj)+lambda(hati+2hatj-hatk)" and "" "...(i)` `r=(hati+hatj)+mu(-hati+hatj-2hatk)" "...(ii)` Now, a vector perpendicular to the given vectors (i) and (ii) is `n=|{:(" "hati,hatj," "hatk),(" "1,2,-1),(-1,1,-2):}|` `=hati(-4+1)-hatj(-2-1)+hatk(1+2)` `=-3hati+3hatj+3hatk` `:.`The equation of plane containing given vecotrs (i) and (ii) is `-3(x-1)+3(y-1)+3(z-0)=0` `implies" "-3x+3y+3z=0` `implies" "x-y-z=0" "...(iii)` Now, the length of perpendicular drawn from the point (2, 1, 4) to the plane `x-y-z=0`, is `d_(1)=(|2-1-4|)/(sqrt(1+1+1))` `=(3)/(sqrt(3))=sqrt(3)` |
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