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

Answer: (D)

(1, – 2, – 1)

Answer 2

$l ( 1 ) + m ( 0 ) + n ( 2 - 1 ) = 0 \Rightarrow l + n = 0$ and

$l ( - 2 ) + m ( 1 ) + n ( - 4 ) = 0 \Rightarrow 2 l - m + 4 n = 0$

$\therefore l = - \frac { m } { 2 } = - n$.

Hence direction ratios are $( 1 , - 2 , - 1 )$.