Question

Direction ratios of the normal to the plane passing through the points (0, 1, 1), (1, 1, 2)and (-1, 2, - 2) are

• A. (1,1,1)
• B. (2,1,-1)
• C. (1,2,-1)
• D. (1,-2,-1)

Answer 1

The correct option is D (1,-2,-1)

l(1)+m(0)+n(2-1)=0 $\Rightarrow$ 1+n=0
and l(-2)+m(1)+n(-4)=0 $\Rightarrow$ 2l-m+4n=0
$\therefore l=-\frac{m}{2}=-n$.
Hence direction ratios are (1,-2,-1).