LetL be the line of intersection of the planes `2x""+""3y""+""z""=""1` – InterviewSolution

InterviewSolution

1.	LetL be the line of intersection of the planes `2x""+""3y""+""z""=""1`and `x""+""3y""+""2z""=""2`. If L makes an angles ` alpha `withthe positive x-axis, then cos` alpha `equals`1/(sqrt(3))``1/2`1`1/(sqrt(2))`A. `(1)/(2)`B. 1C. `(1)/(sqrt2)`D. `(1)/(sqrt3)`
Answer» Correct Answer - d Since line of intersection is perpendicular to both the planes, direction rations of the line of intersection is ltbgt `\|[hati,hatj,hatk],[2,3,1],[1,3,2]\|=3hati-3hatj+3hatk` Hence, `cosalpha=(3)/(sqrt(9+9+9))=(1)/(sqrt3)`

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