Question

sec^4 x - tan^4 x = 1+ 2tan^2 x.
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Answer 1

Heya!!

________
⇒sec^4x-tan^4x=1+2tan²x
L.H.S
⇒(sec²x)²-(tan²x)². a²-b²=(a+b)(a-b)

⇒(sec²x+tan²x) (sec²x-tan²x)

⇒sec²x+tan²x(1)

⇒(1+tan²x+tan²x)

⇒1+2tan²x

LHS⇔RHS

Hope this helps you ☺