# Sinusoidal Functions Help

1. Mar 24, 2015

### Sonny18n

1. The problem statement, all variables and given/known data
A graph of y=f(x) is shown. Find the following function values and justify your answers.

f(30)=
f(-14)=

2. Relevant equations

3. The attempt at a solution
I know the graph is periodic, I know it's max and min, and I know it's amplitude because of that. But I don't know what the 30 or -14 is supposed to mean to me or how I'm suppose to "justify" my answer

2. Mar 24, 2015

### Dick

It looks to me like what you are supposed to conclude from the graph is that f(x+4)=f(x). That's periodic. So f(-14)=f(-10)=f(-6)=f(-2). The last value you can read off from the graph. Patterns like that.

3. Mar 24, 2015

### Pierce610

f(30) and f(-14) are the values of the function calculated in x=30 and x=-14.
You said that the graph is periodic, so it means that the graph repeat itself with perod 5.
now you should obtain the two values.

4. Mar 24, 2015

### Pierce610

Yes, Dick is right, the period is 4

5. Mar 24, 2015

### SammyS

Staff Emeritus
(It is possible for you to Edit post #3. )

6. Mar 24, 2015

### Pierce610

Now no more; I'll do it in future if I should realize in time to have to correct my post

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