I am stuck in this question for a while. Please help me out. Question is simple but I am not able to find the exact answer.
prove that the planes $$ ny-mz = λ , lz- nx =μ $$and $$ mx - ly =ν $$ have a common line if$$ lλ + mμ + n ν =0 $$ . show that the distance of the line from the origin is $$ \sqrt {\frac{ λ^2 + μ^2 + ν^2} {l^2 + m^2 + n^2}} $$
I got the first part but it's second part that's is troubling me. Please , can anyone help me with this question. Thanks in advance.