sin(t)csc(pi/2 - t) = tan(t)
sin (t) csc(pi/2 - t) =
sin (t) / sin (pi/2 - t) =
sin (t) / [ sin (pi/2) oos (t) - sin(t)cos (pi/2) ] =
sin (t) / [ (1)* cos(t) ] =
sin (t) / cos (t) =
tan (t)