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The distance of line 3 y-2 z-1=0=3 x-z+4 from the point (2,-1,6) is :
Option: 1 2 \sqrt{5}
Option: 2 2 \sqrt{6}
Option: 3 \sqrt{26}
Option: 4 4 \sqrt{2}

Answers (1)

best_answer

Let PQ be perpendicular to the given line

Now Q lies on both the planes,

So 3a-2c-1= 0---\left ( i \right ) and
     3a-c+4= 0---\left ( ii \right )

Also\: PQ\perp line\Rightarrow PQ\perp \left ( \vec{n_{1} }\times\vec{n_{2}} \right )
\Rightarrow \vec{PQ}\cdot \left ( \vec{n_{1}} \times \vec{n_{2}}\right )= 0
\Rightarrow\left [ \vec{PQ}\; \; \vec{n_{1}} \; \; \vec{n_{2}} \right ] = 0
\Rightarrow \begin{vmatrix} a-2&b+1 &c-6 \\ 3& 0 & -1\\ 0&3 &-2 \end{vmatrix}= 0
\Rightarrow 3\left ( a-2 \right )-\left ( b+1 \right )\left ( -6 \right )+\left ( c-6 \right )9= 0
\Rightarrow a-2+2b+2+3c-18= 0
\Rightarrow a+2b+3c= 18---\left ( iii \right )

Solving (i),(ii) & (iii)

a= 0,b= 3,c= 4\Rightarrow Q\left ( 0,3,4 \right )
PQ= 2\sqrt{6}

Posted by

Kuldeep Maurya

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