sec ^6 A−tan ^6A=(1+tan ^2A−tan ^2 A)(1+tan ^4
A+2tan ^2 A+tan ^2 A+tan ^4 A+tan ^4 A)
sec ^6 A−tan ^6 A=1+3tan ^2 A+3tan ^4A
L.H.S. = R.H.S.
Hence proved
Step-by-step explanation:
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