1+ tan^2x=_______________

1-tan-2x-equals-to

1+ tan^2x=_______________
A. sec^2x
B. -sec^2x
C. cosec^2x
D. -cosec^2x

The correct choice is A. sec^2x

We know, sec^2x – tan^2x=1

So, 1+ tan^2x=sec^2x.