incircle and circumcircle Given a triangle $\Delta ABC$ with circumcenter $O$, and incenter $I$.
If $∠ABC = 45°$, $OI = d$, and $c − b = d√2$,
Find the value of $\sin A$.
I've thought of using the fact that $d^2 = R(R-2r)$ where $R$ is the circumradius and $r$ is the inradius. But I didn't know where to apply it.

keep going:$\ (4+2\sqrt{2})x^3-(2+2\sqrt{2})x^2-(2+3\sqrt{2})x+(3+\sqrt{2})=4x^3-2\sqrt{2}x^2+2\sqrt{2}x^3-2x^2-3\sqrt{2}x+3-2x+\sqrt{2}=2\sqrt{2}x^2*(\sqrt{2}x-1)+2x^2(\sqrt{2}x-1)-3(\sqrt{2}x-1)-(\sqrt{2})(\sqrt{2}x-1)=(\sqrt{2}x-1)[(2\sqrt{2}+2)x^2-(3+\sqrt{2})]$=0
$\ x=\sqrt{2}/2$ 
or 
$\ x^2=(3+\sqrt{2})/(2\sqrt{2}+2)$    ie $\ x=\sqrt{(2\sqrt{2}-1)/2} $
now you can know $\sin A$
