Answer:
y=n*pi, where n is an integer.
Explanation:
We have the equation:
Which is autonomous because the independent variable does not appear explicitly.
Now, we are asked about all the equilibrium solutions for such autonomous equation. Let's remember that the solution equilibrium y=y0 when F(y0)=0.
Then, matching the given equation to zero, we have:
Which is fulfilled when the sine function has a value of zero. The sine function is worth zero in y=n*pi where n is an integer.