Example 7--Page 2

We are very happy that we get this far. Using our compare strategy, we know that the terms in the parenthesis should equal to . In which there is no , using (which we can get from the condition) we can transform to . Using the same way as we did above, we get:

Converting sum to product, we have:

The identity has been proven.

This is a really good problem, once you understand the process of solving this identity, and you know the strategies, you are in very good shape. Try to think why we take steps like that. You will be surprised at how far you have already come.