Question 3.36: Determine the relative positions of two lines S11 = x0^→ + S...
Determine the relative positions of two lines S^{1}_{1} =\overrightarrow{x_{0} }+S_{1} and S^{1}_{2} =\overrightarrow{y_{0} }+S_{2} in R³ (see Fig. 3.13).

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Remind that both S_{1} and S_{2} are one-dimensional vector subspaces of R³ and \overrightarrow{y_{0} }-\overrightarrow{x_{0} } is a vector in R³.
In case S_{1}=S_{2} : then \overrightarrow{x_{0} }=\overrightarrow{y_{0} } will induce that S^{1}_{1} is coincident with S^{1}_{2}, while \overrightarrow{x_{0} }\neq \overrightarrow{y_{0} } will result in the parallelism of S^{1}_{1} with S^{1}_{2}.
In case S_{1} \cap S_{2} = \left\{\overrightarrow{0}\right\}: then the condition \overrightarrow{x_{0} }-\overrightarrow{y_{0} } \in S_{1}\oplus S_{2} implies that S^{1}_{1} intersects S^{1}_{2} at a point, while \overrightarrow{x_{0} }-\overrightarrow{y_{0} } \notin S_{1}\oplus S_{2} implies that S^{1}_{1} is skew toS^{1}_{2}.