Let $f(x) = \sin( \arccos( x) )$.

a) First find the derivative by using Chain Rule.
$f'(x) =$

b) Next, we will find the derivative in a different way. Rewrite $f(x)$ without trigonometric functions (Hint: Set up a right triangle with a side $x$). When you have finished this step, $f(x)$ can be written as:
$f(x) =$
Then find the derivative of this equivalent form of $f$.
$f'(x) =$