## Final Answer

## Step-by-step Solution

Problem to solve:

Cancel like terms $\cos\left(x\right)$ and $-\cos\left(x\right)$

Learn how to solve definition of derivative problems step by step online.

$\mathrm{derivdef}\left(0\right)$

Learn how to solve definition of derivative problems step by step online. Find the derivative of cos(x)-cos(x) using the definition. Cancel like terms \cos\left(x\right) and -\cos\left(x\right). Find the derivative of 0 using the definition. Apply the definition of the derivative: \displaystyle f'(x)=\lim_{h\to0}\frac{f(x+h)-f(x)}{h}. The function f(x) is the function we want to differentiate, which is 0. Substituting f(x+h) and f(x) on the limit. The limit of a constant is just the constant.