I was doing practice exercise for differential equations and couldn't wrap my head around this one:
We need to find a differential equation that $y$ satisfies and the $ODE$ should not contain any constants. If the $C_1$ was outside $\sin$, then the answer would be much easier. I tried using different identities, inlcuding: $$\sin(x + y) = \sin(x)\cos(y) + \cos(x)\sin(y)$$ $$\cos(x + y) = \cos(x)\cos(y) - \sin(x)\sin(y)$$
But I just could not eliminate the constant because it is inside $\sin$. Any tips would be much appreciated.