Коэффициент редукции

β = \frac{\cos (atan (\frac{\tan ϕ}{FOS})) \cos (atan (\frac{\tan ψ}{FOS}))}{1 - \sin (atan (\frac{\tan ϕ}{FOS})) \sin (atan (\frac{\tan ψ}{FOS}))}

;