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$$

E=C\left[ 1-B(-1)^ncos\left( n\theta\right) \right]  

$$

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$$

E=\frac{1}{2}K\left( \frac{1+cos\omega_0}{sin\omega_0}\right) ^2 \left( cos\omega - cos\omega_0\right) \qquad \omega_0 \neq 0^o

$$

$$

E=K\left( 1-cos\omega\right)  \qquad \omega_0 = 0^o

$$

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