Prove that (sec A + tan A-1)×(sec A- tan A +1) = 2÷ cot A

1.	Prove that (sec A + tan A-1)×(sec A- tan A +1) = 2÷ cot A
Answer» To prove :\xa0(sec A + tan A -1) (sec A - tan A + 1) = 2 tan ALHS = (sec A + tan A - 1)(sec A - tan A + 1)= sec2 A - sec A. tan A + sec A + tan A. sec A -tan2 A + tan A - sec A + tan A - 1= sec2A - tan2 A + 2 tan A - 1= 1 + 2 tan A - 1= 2 tan A= RHSHence proved.

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