Throughout this book, key problems have been selected as “checkpoints.” Each checkpoint problem is marked with an icon like the one at left. These checkpoint problems are provided so that you can check to be sure you are building skills at the expected level. When you have trouble with checkpoint problems, refer to the review materials and practice problems that are available in the Checkpoint Materials.

This problem is a checkpoint for finding the distance between two points and finding the equation of a line. It will be referred to as Checkpoint 2A.

For each pair of points, determine the distance between them. Then find the equation for a line through them.

Check your answers by referring to the Checkpoint 2A materials located at the back of your book.

Ideally, at this point you are comfortable working with these types of problems and can solve them correctly. If you feel that you need more confidence when solving these types of problems, then review the Checkpoint 2A materials and try the practice problems provided. From this point on, you will be expected to do problems like these correctly and with confidence.