sin/cos Graphs

[killasnake]

Hi I'm having trouble with these graphs, I don't know how to get the AMP or the period.

has amplitude _________ and period ________ .

and

shows the graph of the function
f(x) = _________________

Your answer may be of the form f(x)= asin(bx+c) where a, b, and c are small integers or Pi

 

[Gene]

The marks are .2 apart.
The first crossing is at x=.3
The third crossing is at x=2.3
The fifth crossing is at x=4.3
The seventh crossing is at x=6.3
The period is 2. They don't really say so, but I would say the x numbers are units of pi so 2 is really 2*pi.
That makes the starting vally at -.2 which seems to be where it starts at y=-3.
The first peak is harder to see but it must be at x=.8, y=3 so the amplitude is 3.

The second works the same way. Determine the spacing of the marks both vertically and horizontaly. They tell you that a, b & c are integers which helps.
a is the amplitude.
b is the number of cycles in 2*pi.
c is the shift to the right or left.

 

[killasnake]

So what I got was

2sin[(pi*x) +(pi^2)/5]

which is wrong... :?

btw this is for the second graph

 

[Gene]

They said it was of the form
f(x)= asin(bx+c)
2sin[(pi*x) +(pi^2)/5]
I don't know where you got the pi^2/5. I can't see c as an integer though.
You got a=2 correct.
There is one cycle in 2pi so b=1*pi and you got that right.
From the graph it looks like the shift is -.7pi.
That would make the equation
2sin(pi*x+.7*pi)
so that when x= -.7pi it becomes sin(0) where the crossing is.