Equation Icon  ( ) 2 F (y) 1 + y 2 ds = − ----- dt − C R ------dψ F (x ) F(y) R2 [ G (y ) dy2 dx2 G (x) ] + --------F (x) − -----dψ2 − ----- + ----- + -----dφ2 , (50 ) (x − y)2 F (y ) G (y) G (x) F (x)