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]
1.6m questions
2.0m answers