Respuesta :

Step-by-step explanation:

[taking alpha = a]

L.H.S.

(1-sin⁴a)/cos⁴a

= 1/cos⁴a-sin⁴a/cos⁴a

= sec⁴a-tan⁴a

= (sec²a+tan²a)(sec²a-tan²a)

= (1+tan²a+tan²)(1) [as sec²a=1+tan²a]

= 1+2tan²a

= R.H.S. [Proved]

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