# addition or subtraction for cofunction identity

• May 7th 2010, 05:10 PM
pmacp
addition or subtraction for cofunction identity
I have no idea how to work this problem using addition or subtraction theories (Worried)

(x-n) = -sin x

Thanks!
• May 7th 2010, 06:05 PM
dwsmith
Quote:

Originally Posted by pmacp
I have no idea how to work this problem using addition or subtraction theories (Worried)

(x-n) = -sin x

Thanks!

What are you trying to do? What is the whole the question verbatim?
• May 7th 2010, 06:18 PM
pmacp
Prove the confunction identity sin (x - π) = -sin x using the addition or subtraction formulas.
• May 7th 2010, 06:21 PM
dwsmith
$sin(x-\pi)=sin(x)cos(\pi)-cos(x)sin(\pi)=-sin(x)$
• May 7th 2010, 06:25 PM
pmacp
thank you!