the derivative wrt x of -sin(2x) is -2cos(2x), not -2sin(2x)cos(2x) as you have it in the solution to the goat problem. -- James Richard Spriggs at jrspriggs2000@yahoo.com

## wrong derivative

the derivative wrt x of -sin(2x) is -2cos(2x), not -2sin(2x)cos(2x) as you have it in the solution to the goat problem. -- James Richard Spriggs at jrspriggs2000@yahoo.com