Thread: Need Help Simplifying: [(cosxcotx)/(secx+tanx)] + (sinx)/(sex-tanx)]

Hey everybody,

I've been stuck as to how to simplify this: [(cosxcotx)/(secx+tanx)] + (sinx)/(sex-tanx)]y

Apparently it simplifies to sinx, but i have no idea how they got there. Been working on this for about a half an hour now and i keep getting stuck, help?

Thanks!

Originally Posted by princeps

So convert everything to sin and cosine then?

[(cosxcotx)/(secx+tanx)] + (sinx)/(secx-tanx)]
to sin and cosine
[(cos2x/sinx)/(1/cosx+sinx/cosx)+(1/cosx-sinx/cosx)]
group together common denominators
[(cos2x/sinx)/(1+sinx/cosx)+(1-sinx/cosx)]
what now?

If you mean this:



then no - it does not simpify to .

There is an extra close bracket symbol ']' in your original post, and an extraneous 'y' charcter after it in the body of the post, so perhaps I am not interpreting your formula correctly.

Yeah, I wrestled with this one and couldn't make it reduce to sin(x). Just to confirm, I fed it through Mathematica and Mathematica waived a little white flag over it too. So either you copied it wrong or there's a misprint in your book.

I've learned when trying to help people with trig identities - if I can't work it out in 2 minutes or less then I put it in excel and see if it works for a value like x = 0.1. It saves a lot of wasted time...

It's a good lesson for me. I have to learn to let go of a problem before my brain starts hurting...

Originally Posted by ebaines

If you mean this:



then no - it does not simpify to .

Yeah... must've been an error in the textbook. thanks for the help anyways. I appreciate it