Need a Trig Ratios question answered (Sorry for wrong icon :()

[FrontFuze]

I can't understand the process behind doing this, help please

csc(6b+pi/8) = sec(2b-pi/8)

csc is r/y
sec is r/x

What do I have to do next?

Thanks for the help mates.

EDIT: SORRY WRONG ICON!

[DuraFlex]

go to [url]www.webmath.com[/url]