(cos40st./sin50st.) - (sin^2 38st. + sin^2 52 st.)

(cos40st./sin50st.) - (sin^2 38st. + sin^2 52 st.) (cos40st./cos40st.) - (sin^2 38st. + cos^2 38 st.) 1-1=0 wzory: sinα=cos(90-α)