F(x)=cos2x and g(x) =-sin x. Sketch the graphs of f and g on the same set es (-90,90)

2 answers

I can not do much for you. just take some values of x like - 90,-60, - 45, -30, 0 , 30, 45 etc and do your graphs
Excellent graphing help can be had at

http://rechneronline.de/function-graphs/

For your example, I'd enter two functions:

cos(2x*pi/180)
-sin(x*pi/180)
and set the x range from -100 to 100
and set the y range from -1 to 1

The pi/180 factor is needed because it plots the angle in radians, not degrees.