The hints for problems provide both hints and strategies for attacking some of the more difficult end-of-chapter problems. In some cases, the hints provide intuition about how to set up the problem; in other cases, the hints provide explicit mathematical instructions on how to carry through more tricky manipulations.
(TIP: To save the files directly to your computer right-click or alt-click and select 'save target as' or 'save link as' then select a location on your desktop to save the file. Otherwise you may be prompted to open the file first then save to your local computer.)