Prove the following trigonometric identities:
(sec A−tan A)2=1−sin A1+sin A
(sec A−tan A)2=1−sin A1+sin A
LHS=(sec A−tan A)2
=(1cosA−sinAcosA)2
=(1−sinAcosA)2
=(1−sinA)2cos2A
=(1−sinA)21−sin2A
=(1−sinA)(1−sinA)(1−sinA)(1+sinA)
=1−sin A1+sin A
=RHS