Derivatives are defined as the rate of change of any function f(x) with respect to an independent variable.

## Answer: The Derivative of y = cos 2x is − 2 sin 2 x

Let us proceed for this problem step by step

**Explanation:**

On differentiating cos x, we get - sin x. [d/dx cosx = - sin x]

Since cos 2x is a composition of two functions which are cosine function and 2x.

On differentiating 2x, we get 2. [d/dx 2x =2]

So, using chain rule, we have

d y/ d x = − 2 sin 2x