trig functions help (1 Viewer)

wgy182 · Jul 27, 2013

Show that d/dx((cosx+sinx)/(cosx-sinx))=sec^2((pi/4)+x).

I can't write the pi symbol on here so I just wrote the word.
Can anyone solve this?
Thanks in advance

Carrotsticks · Jul 27, 2013

Did you try the Quotient Rule?

wgy182 · Jul 27, 2013

I still can't get it. Can u help me?

HeroicPandas · Jul 27, 2013

Alright now my attempt (an alternative to quotient rule)

$\frac{d}{dx}\left ( \frac{\left cosx + sinx \right }{cosx-sinx}\right )$

Divide every term by cosx

$\frac{d}{dx}\left ( \frac{\left 1 + tanx \right }{1-tanx}\right )$

Notice the reverse tan expansion

$\frac{d}{dx}\left ( tan\left ( \frac{\pi}{4}+x \right ) \right )$

This can be easily differentiated

PLEASE, if there are any mistakes, tell me (recently every post i've made has a mistake (either a small one or the whole thing)

wgy182 · Jul 27, 2013

Yea it's correct, thanks bro

trig functions help (1 Viewer)

wgy182

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Carrotsticks

Retired

wgy182

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HeroicPandas

Heroic!

wgy182

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