Step-by-step explanation:
sec⁴A + tan⁴A = 1 + (2tan²A/cos²A)
LHS = sec⁴A + tan⁴A
= (sec²A)² + (tan²A)² {using formula of a²+b²)
= (sec²A-tan²A) + 2tan²A.sec²A
= 1 + {2tan²A.(1/cos²A)}
= 1 + (2tan²A/cos²A)
