Answer:
see explanation
Step-by-step explanation:
using the identity
tan²x = sec²x - 1
consider the left side
(tanx + secx)² ← expand using FOIL
= tan²x + 2tanxsecx + sec²x
= sec²x - 1 + 2tanxsecx + sec²x ← collect like terms
= 2sec²x + 2tanxsecx - 1
= right side , thus proven
