1. ## Cofunction identity

Im trying to verify the identity cos (X-pi/2)= sin x

Can someone please break down? Literally step by step. And indicate which identities r being used.

Thank you.

2. ## Re: Cofunction identity

Cos (x-pi/2)=cos(x)cos(pi/2)+sin(x)sin(pi/2)

Simplify.

3. ## Re: Cofunction identity

Yes, i figured as much using the sum and difference identity. Dont know what to do afterr that.

4. ## Re: Cofunction identity

Well, cos(pi/2)=0 and sin(pi/2)=1 so you end up with sin(x)=sin(x).

5. ## Re: Cofunction identity

Ohhhhhh....drat...didnt realize had to look at them individually, i was too bz just figuring out how to cancel each other out to get sin x alone. Thanks so much!