Question

How do you verify the identity `cosx+cosxtan^2x=secx`?

Answer 1

Use the following identities:

•`tantheta = sintheta/costheta`
•`sectheta = 1/costheta`

`cosx + cosx xx sin^2x/cos^2x = 1/cosx`

`cosx + sin^2x/cosx = 1/cosx`

`(cos^2x + sin^2x)/cosx = 1/cosx`

Use the identity `sin^2theta + cos^2theta = 1`.

`1/cosx = 1/cosx`

`LHS = RHS`

Hopefully this helps!