Answer:
see explanation
Explanation:
using the identity
tan²x + 1 = sec²x ( subtract 1 from both sides )
tan²x = sec²x - 1 ← factor as a difference of squares
tan²x = (secx - 1)(secx + 1)
consider left side

=
← cancel (secx - 1) on numerator/ denominator
= secx + 1
= right side , hence proven