Question

-tan^2 + sec^2x=1

Answer 1

Use the identity that 1+tan^2x=sec^2x

Answer 2

check your pythagorean identities http://www.ops.org/high/north/Portals/0/ACADEMICS/StaffPages/holleyd/calculushtml01/calc0-4notes8.gif

Answer 3

can you show me how?

Answer 4

notice the 2nd identity in the picture, solve for " 1 "

Answer 5

You need to replace sec^2x with 1+ tan^2x all by yourself.