# How do I find the derivative of #f(x) = sin(2x)cos(2x)#?

##### 1 Answer

Mar 8, 2018

#### Answer:

Either use the product rule and the chain rule or apply a trig identity and only use the chain rule.

#### Explanation:

Personally I prefer the latter option:

I would use the double angle formula:

Trasforming you equation into:

Which can then be differentiated using the chain rule:

Multiply by the derivative of the bracket and differentiate the trig term:

If you want to know the other method, search the 'product rule' in your search engine of choice.