How do you verify the identity cosx+sinxtanx=sec xcosx+sinxtanx=secx?

1 Answer
May 1, 2015

Use the fact that:
tanx=sinx/cosxtanx=sinxcosx
and
secx-1/cosxsecx1cosx
So:
cosx+sinxsinx/cosx=1/cosxcosx+sinxsinxcosx=1cosx
(cos^2x+sin^2x)/(cosx)=1/cosxcos2x+sin2xcosx=1cosx
1/(cosx)=1/cosx1cosx=1cosx

Where I used: sin^2x+cos^2x=1sin2x+cos2x=1