1. The problem asks to determine the relationship between lines AC and RS based on the given diagram and information. 2. Important definitions: - **Coplanar lines** lie in the same plane. - **Parallel lines** are coplanar and never intersect. - **Perpendicular lines** intersect at a right angle. - **Skew lines** are not coplanar and do not intersect. 3. Given that lines AC and RS lie on two different planes (one vertical plane containing AC and one horizontal plane containing RS), they are not coplanar. 4. Since the planes intersect and the lines lie on different planes, the lines AC and RS cannot be parallel or coplanar. 5. The right angle markers indicate that the planes intersect perpendicularly, but the lines themselves are on different planes and do not intersect. 6. Therefore, lines AC and RS are **skew lines** because they are not coplanar and do not intersect. Final answer: Lines AC and RS are skew.