- $${\omega ^2}\left( {{{\text{r}}_1}{{\text{r}}_2}} \right)\left( {1 - {{\cos }^2}\theta } \right)$$
- $${\omega ^2}\left( {{{\text{r}}_1} + {{\text{r}}_2}} \right)\left( {1 + {{\cos }^2}\theta } \right)$$
- $${\omega ^2}\left( {{{\text{r}}_1} + {{\text{r}}_2}} \right)\left( {\frac{{2 - {{\cos }^2}\theta }}{{{{\cos }^3}\theta }}} \right)$$
- $${\omega ^2}\left( {{{\text{r}}_1} - {{\text{r}}_2}} \right)\left( {1 - {{\sin }^2}\theta } \right)$$