# Thread: Trig Proof Issue..

1. ## Trig Proof Issue..

I am currently smashing my face into my desk from frustration of this trig proof. People have told me it's easy, but for whatever reason, I can not for the life of me figure out how to do it. The problem is:

(sin³x + cos³x) / (sinx + cosx) = (1 - sinx cosx)

Any help with this would be greatly apperciated..

Thanks in advance!

2. Originally Posted by Ramar
I am currently smashing my face into my desk from frustration of this trig proof. People have told me it's easy, but for whatever reason, I can not for the life of me figure out how to do it. The problem is:

(sin³x + cos³x) / (sinx + cosx) = (1 - sinx cosx)

Any help with this would be greatly apperciated..

Thanks in advance!
Do you remember the formula for factoring the sum of cubes.

$A^3+B^3=(A+B)(A^2-AB+B^2)$

This should finish the proof for you.

Good luck.

3. Holy cow. I can't believe I missed that. lol thanks for the help and the quick response. =)