The direction cosines of the line which is perpendicular to the lines with direction ratios 1, -2, -2 and 0, 2, 1 are:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → $\frac{2}{3},-\frac{1}{3}, \frac{2}{3}$
DRs → 1, -2, -2 = DRI
DRs → 0, 2, 1 = DRII
DR's perpendicular = cross (DRI × DRII)
= 2, -1, 2
DCs = $\frac{2,-1,2}{\sqrt{2^2+1^2+2^2}}=\frac{2}{3},-\frac{1}{3}, \frac{2}{3}$