
\magnification=\magstep1




$$
\delta \quad = \quad { { \left ( {{R_p} \over {R_s}} \right )}^2 }
$$

$$
\theta \quad \simeq \quad { {R_s} \over {a} }
$$

$$
{ { 2 \theta} \over { 2 \pi } } \quad = \quad { {T} \over {P} }
$$

$$
{{T}\over{P}} \quad = \quad { {R_s} \over {\pi a} }
$$

$$
{P}^2 \quad = \quad {{ 4 \pi^2} \over { {{4}\over{3}} \pi G \rho_s }} 
                       \left ( { {a^3} \over {R_s}^3 }  \right ) 
$$

$$
\rho \quad = \quad { \left( {{3 \pi}\over{G P^2}} \right) }
                  \thinspace {\left( {{a}\over{R_s}} \right)}^3
$$




\bye
