I already told you that all angles should be in radians  or you keep getting 2pi all over the place. For a start  your derivative is only correct if ω is in radians. Look up differentiating trig functions  basics of. Degrees suck in Science. Radians will be used all over the Universe (literally) by any civilisation with Maths but degrees are totally arbitrary.
I don't know what those equations mean as you didn't define the variables so it is not possible to derive them.
The "w" on the left hand side is not omega! And what is the theta? Is this describing a tortional vibration? Those angles aren't the same angles as the angular velocity in the vibration cycle. See how confusing it is when the variables aren't defined.
