Last week we started chapter 8. I had more trouble with 8-1 than 8-2. 8-2 was pretty much finding the amplitude and period with a possible shift change. But learning 8-3 helped with the previous sections.

In case of a period change you must:
1) take all five points
2) divide by whatever b is
3) sketch your graph

Amplitude is the distance from 0 to the highest point and 1/2 the vertical distance.
Period is how long it takes for the function to repeat itself.

Example:
y=2sin3x
since it is sin your graph will start at the origin.
first you must find the amplitude
the amplitude is 2.
to find the period you divide 2pi by b which is 3.
your period is 2pi/3.

Next you must take all the points on the graph and divide them by your period.
0 0/3=3
pi/2 pi/2/3=pi/2x1/3 =pi/6 (when dividing you must multiply by the reciprocal.
pi pi/3
3pi/2 3pi/2/3=3pi/2x1/3 =3pi/6=pi/2
2pi 2pi/3

Once you have found all your points you can sketch your graph.
Since your amplitude is 2 you must make sure your graph repeats itself twice.