trigonometric functions

1. - cos x means reflects the curve about the x - axis.
+ 1 means shifting the - cos x curve upwards by 1 unit.
2. sin x/2 means to enlarge a cycle from 360 degree to 720 degree. That is half a cycle for 360 degree. +1 means shifting the sin x/2 curve upwards by 1 unit.
3.
g(x) has been reducing 1 cycle to 2 cycles , so g(x) = cos 2x.
h(x) has been enlarging 1 cycle to 1/2 cycle, so h(x) = cos x/2.