# definition of derivation

1. ### Derivation using the definition of a derivite

The question I am struggling with is as follows: My working is as follows: I don't know how to continue from here or even rather if i'm on the right track. Thank you in advance for any help!
2. ### SOLVED Definition of Derivative/Alt. form of the derivative

My teacher assigned this as a review for the test. This particular question looks like definition of derivative to me: \displaystyle \lim_{h \to 0} \frac{f(x+h)- f(x)}{h} Would that make f(x + h) = sin x and f(x) = 1/2? I'm very confused on which parts are which.