The general form will be

Since A is the amplitude, this part is easy: A = 3.

Now, we want a 0 of the sine function to be positioned at . We can do this by setting at , so we have the equation:

Again, we want a 0 of the sine function to be positioned at . We can do this by setting ( is the next zero for the sine function after 0) at , so we have the equation:

Solving the first equation for gives:

Inserting this into the second equation gives:

or

This gives

.

Thus

.

-Dan