The Pythagorean identities are building blocks for many of the manipulations of trigonometric equations and expressions. They provide a greater number of methods for solving trig problems more efficiently, because they allow you to write complicated expressions in a much simpler form.
The Pythagorean identities are
![image0.png](https://www.dummies.com/wp-content/uploads/275572.image0.png)
The notation in these identities is peculiar to trigonometry.
![image1.png](https://www.dummies.com/wp-content/uploads/275573.image1.png)
So they agreed on a condensed version: The superscript 2 right after “sin” means that you square the whole expression. The same type of notation also goes for the other functions.