10 Given $f(1+\sin x)=\cos 2 x-3 \sin x, f(x)=$
\[
\begin{array}{l}
10-2 x^{2}+x+2 . \quad f(1+\sin x)=1-2 \sin ^{2} x-3 \sin x=-2(1+\sin x)^{2}+ \\
(1+\sin x)+2 \text {, so } f(x)=-2 x^{2}+x+2 .
\end{array}
\]