How do you find the derivative of # y=sin^2x cos^2x#?
Use the product rule:
Use the chain rule to find both derivatives:
There is the identity that
There is something that makes the answer a lot simpler to find.
You can also remember that
The derivative of
The advantage of those trigonometric identities is for physicists, they can find every piece of information in the wave that this function represents. They're also very useful when you have to find primitives of trigonometric functions.