Question

How do you verify the identity `cosx+sinxtanx=sec x`?

Answer 1

Use the fact that:
`tanx=sinx/cosx`
and
`secx-1/cosx`
So:
`cosx+sinxsinx/cosx=1/cosx`
`(cos^2x+sin^2x)/(cosx)=1/cosx`
`1/(cosx)=1/cosx`

Where I used: `sin^2x+cos^2x=1`