Q.

If the line 2x3=3y24λ+1=4z makes a right angle with the line x+33μ=12y6=5z7, then 4λ+9μ is equal to :          [2024]

1 13  
2 6  
3 5  
4 4  

Ans.

(2)

We have lines 2x3=3y24λ+1=4z and x+33μ=12y6=5z7 are perpendicular.

i.e., x23=y2/34λ+13=z41 and x(3)3μ=y1/262=z57 are perpendicular.

3(3μ)+4λ+13(3)+(1)(7)=0

9μ4λ1+7=0

9μ4λ+6=0  4λ+9μ=6.