9514 1404 393
Answer:
sec² x
Step-by-step explanation:
It is a trig identity that ...
tan² x + 1 = sec² x
_____
If you like, you can convince yourself of this using the usual equivalents for tan and sec:
tan² x + 1 = sin² x/cos² x +1 = (sin² x + cos² x)/cos² x = 1/cos² x = sec² x
