# Sin equation formula

1. Mar 4, 2014

### datafiend

1. The problem statement, all variables and given/known data

Find the amplitude, period, phase shift, and vertical shift
2. Relevant equations

y=- $1/2$sin [3 (x-∏/2)] -2

3. The attempt at a solution
amp = -$1/2$, vertical shift is 2 down y-axis.

I can't get the period and ph. shift.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Mar 5, 2014

### HallsofIvy

The "standard" sine function, sin(x), has one period starting at $x= 0$ and ending at $x= 2\pi$. The function sin(a(x- b)) has one period starting at $a(x- b)= 0$, or $x= b$ and ending at $a(x- b)= 2\pi$ or $x= b+ \frac{2\pi}{a}$.