Posted by Anonymous on Sunday, September 23, 2012 at 2:19am.
Find the xcoordinates of all points on the curve
f(x) = sin 2x − 2 sin x
at which the tangent line is horizontal. (Enter your answers as a commaseparated list. Use n to represent any integer.)

calculus  Steve, Sunday, September 23, 2012 at 7:43am
tangent is horizontal when f'(x) = 0
f'(x) = 2cos2x  2cosx
f'(x) = 0 when x = 2k*pi or 2k*pi +/ 2pi/3
for all integers k