These diagrams should help students who are stuck on Big Idea 7.1
Original Diagram for Big Ideas 7.1
This is the original diagram showing which pairs of sides are parallel.
Notice that the left sides of the four triangles are parallel and they are cut by a horizontal transversal. (Hint: You might want to review the lessons on parallel lines and transversals in chapter 3, which was covered in first semester Geometry.)
Notice that the right sides of the four triangles are parallel and they are cut by a horizontal transversal.