Question 41472
<pre><font size = 4><b>
graph y=3sinx and y=sin 3x on the same axes. 
label the graph of each function.

I know the amp. of first function is 3 and
period is 2<font face = "symbol">p</font> and for second function amp. is 1 
and period is 2<font face = "symbol">p</font>/3 i just dont know how to graph

=======================================================

Draw the y-axis long enough to include both amplitudes 
as well as the opposite signs of the amplitudes:

 3|-
  |
 2|-
  |
 1|- 
  |
 0|-----------------------------------------------------------------------
  |
-1|-
  |
-2|-
  |
-3|- 

Divide the period of each by 4. 

Dividing the first function's period by 4: 2<font face = "symbol">p</font>÷4 is <font face = "symbol">p</font>/2
Multiply this by 0, 1, 2, 3, and 4

0<font face = "symbol">p</font>/2, 1<font face = "symbol">p</font>/2, 2<font face = "symbol">p</font>/2, 3<font face = "symbol">p</font>/2, 4<font face = "symbol">p</font>/2

or, reducing:

0, <font face = "symbol">p</font>/2, <font face = "symbol">p</font>, 3<font face = "symbol">p</font>/2, 2<font face = "symbol">p</font>

Positive sine functions go x-intercept, maximum, x-intercept, minimum,
x-intercept. 

Therefore it will have an x intercept at 0, a maximum at <font face = "symbol">p</font>/2, 
an x-intercept at <font face = "symbol">p</font>, a minimum at 3<font face = "symbol">p</font>/2 and an x-intercept at 2<font face = "symbol">p</font>

Dividing the second function's period by 4: (2<font face = "symbol">p</font>/3)÷4 is <font face = "symbol">p</font>/6

Multiply this by 0, 1, 2, 3, and 4

0<font face = "symbol">p</font>/6, 1<font face = "symbol">p</font>/6, 2<font face = "symbol">p</font>/6, 3<font face = "symbol">p</font>/6, 4<font face = "symbol">p</font>/6

or, reducing:

0, <font face = "symbol">p</font>/6, <font face = "symbol">p</font>, <font face = "symbol">p</font>/3, 2<font face = "symbol">p</font>/3

Positive sine functions go x-intercept, maximum, x-intercept, minimum,
x-intercept. 

Therefore it will have an x intercept at 0, a maximum at <font face = "symbol">p</font>/6, 
an x-intercept at <font face = "symbol">p</font>, a minimum at <font face = "symbol">p</font>/3 and an x-intercept at 2<font face = "symbol">p</font>/3

The LCD of periods <font face = "symbol">p</font>/6 and <font face = "symbol">p</font>/2 is 6, so mark off the x-axis in units of 
<font face = "symbol">p</font>/6, that is

1<font face = "symbol">p</font>/6, 2<font face = "symbol">p</font>/6, 3<font face = "symbol">p</font>/6, 4<font face = "symbol">p</font>/6, 5<font face = "symbol">p</font>/6, ... , 12<font face = "symbol">p</font>/6

 3|-
  |
 2|-
  |
 1|- 
  |
-0|----·----·----·----·----·----·----·----·----·----·----·----·------   
  |  <font face = "symbol">p</font>/6  2<font face = "symbol">p</font>/6 3<font face = "symbol">p</font>/6 4<font face = "symbol">p</font>/6 5<font face = "symbol">p</font>/6 6<font face = "symbol">p</font>/6 7<font face = "symbol">p</font>/6 8<font face = "symbol">p</font>/6 9<font face = "symbol">p</font>/6 10<font face = "symbol">p</font>/6 11<font face = "symbol">p</font>/6 12<font face = "symbol">p</font>/6
-1|-
  |
-2|-
  |
-3|-

I stopped at 12<font face = "symbol">p</font>/6 because that equals 2<font face = "symbol">p</font>, the larger period.

Reducing the ones of those that will reduce:

<font face = "symbol">p</font>/6, <font face = "symbol">p</font>/3, <font face = "symbol">p</font>/2, 2<font face = "symbol">p</font>/3, 5<font face = "symbol">p</font>/6, <font face = "symbol">p</font>, 7<font face = "symbol">p</font>/6, 4<font face = "symbol">p</font>/3, 3<font face = "symbol">p</font>/2, 5<font face = "symbol">p</font>/3, 11<font face = "symbol">p</font>/6, 2<font face = "symbol">p</font>.

 3|-
  |
 2|-
  |
 1|-
  | 
-0|----·----·----·----·----·----·----·----·----·----·----·----·------   
  |   <font face = "symbol">p</font>/6  <font face = "symbol">p</font>/3  <font face = "symbol">p</font>/2 2<font face = "symbol">p</font>/3 5<font face = "symbol">p</font>/6   <font face = "symbol">p</font>  7<font face = "symbol">p</font>/6 4<font face = "symbol">p</font>/3 3<font face = "symbol">p</font>/2 5<font face = "symbol">p</font>/3 11<font face = "symbol">p</font>/6 2<font face = "symbol">p</font>
-1|-
  |
-2|-
  |
-3|-

Note that those values on the x-axis are about

.5, 1, 1.6, 2.1, 2.6, 3.14, 3.7, 4.2, 4.7, 5.2, 5.8, 6.28 

So the two graphs are

{{{ graph( 300, 100, 0, 6.28, -3, 3, sin(3*x)*sqrt(2.1-x)/sqrt(2.1-x), 3*sin(x)) }}}

But you should extend the graph of y = sin(3x) to the
length of the period of the graph of y = 3sin(x) like
this:

{{{ graph( 300, 100, 0, 6.28, -3, 3, sin(3*x), 3*sin(x)) }}}

You should also leave the x-axis markings in terms of <font face = "symbol">p</font>,
rather than their numerical values as are on the graphs above. 

Edwin
AnlytcPhil@aol.com</pre>