I need help on this problem: The depth of the water, f(x) in meters for a particular body of water is given as a function of time, x, in hours after midnight by the function f(x)=10+7.5cos(0.2x). Find f'(x). f'(x)=______ How quickly is the tide rising or falling, in meters per hour at 6am?(Round to 4 decimal places) Answer:______m/hr