1. The problem statement, all variables and given/known data How are the two lines r = i + 2j + t(i - k), and r = k + s(-i + k) parallel? t,s∈ℝ 2. Relevant equations parametric vector equation of a line [tex]r-r_0=tv[/tex] 3. The attempt at a solution Tried to find the conditions for lines to be parallel in ℝ^3.