Question 1170198
{{{y=A*sin(Bx)+D}}} or {{{y=A*cos(Bx)+D}}}
<pre>
The amplitude is |A|
The period is 2&pi;/B
The midline is y=D

{{{y=2sin(expr(1/3)x)+1}}} 

The amplitude is |2|, which = 2
The period is {{{2pi/expr(1/3)}}}, which is {{{6pi="18.8......"}}} 
The midline is y=1

{{{drawing(400,8000/39,-.5,19,-4,6, circle(3pi,1,.2),
circle(3pi/2,3,.2),locate(3,4.7,(matrix(1,3,3pi/2,",",3))),
locate(9.8,1.8,(matrix(1,3,3pi,",",1))),

circle(0,1,.3),

locate(15.4,1.8,(matrix(1,3,6pi,",",1))),circle(6pi,1,.2),

locate(0,1,"(0,1)"),

circle(9pi/2,-1,.2),locate(12,-1.1,(matrix(1,3,9pi/2,",",-1))),

graph(400,8000/39,-.5,19,-4,6,2sin(x/3)+1,1))}}}

The 5 important points are marked.

Edwin</pre>