Respuesta :

R.H.S = 1/sintheta - sintheta/sintheta = csctheta - 1

cot^2theta = csctheta^2 - 1 = (csctheta - 1) (csctheta+1)

L.H.S = (csctheta - 1)(csctheta+1)/1+csctheta = cscstheta - 1 = R.H.S