The Total solution for NCERT class 6-12
(1 – cos2 A)cosec2 A = 1L.H.S. = (1 – cos2 A) cosec2 A = sin2 Acosec2 A (∵ 1 – cos2 A = sin2 A)= (sin A cosec A)2 = (l)2 = 1 = R.H.S. {sin A cosec A = 1 }