2. Think of the parallel lines being the walls of a building, and the transversal is a firewall through the building, and a door in the firewall.

3. The blue area is the interior (inside), the white area is the exterior (outside). To alternate sides, you have to go through the door. Thus this area and this area are both exterior, and to get from one to the other you have to go through the door (alternate), making these alternate exterior angles

4. The blue area is the interior (inside), the white area is the exterior (outside). To alternate sides, you have to go through the door. This area and this area are also both exterior, and to get from one to the other you have to go through the door (alternate), making these alternate exterior angles also.

5. The blue area is the interior (inside), the white area is the exterior (outside). To alternate sides, you have to go through the door. This area and this area are both interior, and to get from one to the other I have to go through the door (alternate), making these alternate interior angles

6. The blue area is the interior (inside), the white area is the exterior (outside). To alternate sides, you have to go through the door. Likewise, this area and this area are both interior, and to get from one to the other I have to go through the door (alternate), making these alternate interior angles also.

7. The blue area is the interior (inside), the white area is the exterior (outside). To alternate sides, you have to go through the door. This area and this area are both interior, and to get from one to the other I just have to go next door (consecutive), making these consecutive interior angles.

8. The blue area is the interior (inside), the white area is the exterior (outside). To alternate sides, you have to go through the door. Likewise, this area and this area are both interior, and to get from one to the other I just have to go next door (consecutive), making these consecutive interior angles also.

9. For locations to correspond, one has to be outside, and one inside, but both be in the same relative location. This area and this area are both on the right of the firewall, and have a wall to the north, but one is outside and one inside—making these locations corresponding.

10. For locations to correspond, one has to be outside, and one inside, but both be in the same relative location. This area and this area are both on the left of the firewall, and have a wall to the north, but one is outside and one inside—making these locations corresponding.

11. For locations to correspond, one has to be outside, and one inside, but both be in the same relative location. This area and this area are both on the right of the firewall, and have a wall to the south, but one is outside and one inside—making these locations corresponding.

12. For locations to correspond, one has to be outside, and one inside, but both be in the same relative location. This area and this area are both on the left of the firewall, and have a wall to the south, but one is outside and one inside—making these locations corresponding.