Skip to main contentSkip to solution

If the lines x+13=y+35=z+λ7\dfrac{x+1}{3}=\dfrac{y+3}{5}=\dfrac{z+\lambda}{7} and x−21=y−43=z−65\dfrac{x-2}{1}=\dfrac{y-4}{3}=\dfrac{z-6}{5} are intersecting , then the value of 'λ\lambda' is

Solution

✅ Correct Option: 3

Intersecting lines are coplanar, so the scalar triple product of the joining vector (3,7,6+λ)(3,7,6+\lambda) with the two directions (3,5,7)(3,5,7) and (1,3,5)(1,3,5) must vanish. Expanding gives 3(4)−7(8)+4(6+λ)=4λ−20=03(4)-7(8)+4(6+\lambda)=4\lambda-20=0, hence λ=5\lambda=5.

Keyboard Shortcuts

  • Left arrow: Previous question
  • Right arrow: Next question
  • S key: Jump to solution
  • Q key: Jump to question