Here's the question you clicked on:
tux
Given y=sin(2x), then dy/dx at x=3 most nearly is: A) 0.9600 B) 0.9945 C) 1.920 D) 1.989 My answer is D)1.9890 but in the solutions answer is 1.920.
the unit is probably radians not degrees
When I convert it to radians I get http://www.wolframalpha.com/input/?i=1.989+degrees+to+radians
you don't have to convert,just set the mode in your calculator to radians then you'll get 2*cos(6)=1.9203...