# Simplifying the Trigonometric Expression Question

1. Apr 19, 2009

### Deaddman

1. The problem statement, all variables and given/known data

cosx/(secx+tanx)

3. The attempt at a solution

So far I have this:

=cosx/(1/cosx + sinx/cosx)
=cosx/(sinx + 1/cosx)
=cos2x/sinx + 1

From there I don't know what to do. I've messed around with it for a while but don't seem to get anywhere.

Any help is appreciated.

Last edited: Apr 19, 2009
2. Apr 19, 2009

### Russell Berty

Your last denominator is incorrect. It should be sinx + 1.

3. Apr 19, 2009

### Deaddman

Yeah you're right, thanks for pointing it out. Fixed now.

4. Apr 19, 2009

### yeongil

cos2 x/(1 + sin x)
(Let's keep the order of 1 and sin x.)

Here's a hint: do you know of an identity that has a sin x (or a multiple or a power thereof) and a cos x (as before) in it?

01

5. Apr 20, 2009

### Deaddman

Ahhh, I think I got it.

1-sin2 x/1+sin x

(1-sin x)(1+sin x)/1+sin x

1-sin x!

Right?

6. Apr 20, 2009

### yeongil

Indeed that is correct!

01

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