InterviewSolution
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InterviewSolution
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A non vector `veca` is parallel to the line of intersection of the plane determined by the vectors `hati,hati+hatj` and thepane determined by the vectors `hati-hatj,hati+hatk` then angle between `veca and hati-2hatj+2hatk` is = (A) `pi/2` (B) `pi/3` (C) `pi/6` (D) `pi/4`A. `(pi)/2`B. `(pi)/3`C. `(pi)/6`D. `(pi)/4` |
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Answer» Correct Answer - D The line of intersection of the two planes is perpendicular to their normals. So, it parallel to the vector `veca={(hatixx(hati+hatj)}xx{(hati-hatj)xx(hati=hatk)}` `impliesveca=hatkxx(-hatj+hatk-hatk)=hati-hatj` Let `theta` be the angle between `veca` and `vecb-hati-2hatj+2hatk`. Then `cos theta=(veca.vecb)/(|veca||vecb|)=3/(sqrt(2)xx3)=1/(sqrt(2))impliestheta=(pi)/4` |
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