8. $P$ is any point inside $\triangle A B C$, let $P A=x, P B=y, P C=z$, then when $x \cdot \sin A+$ $y \cdot \sin B+x \cdot \sin C$ takes the minimum value, the position of point $P$ is $\qquad$ .
8. Orthocenter

Draw the projections $X, Y, Z$ of $P$ onto the three sides, then $X, Y, P, C$ are concyclic, thus $XY = PC \cdot \sin C = Z \sin C$ reasoning $YZ = x \sin A, ZX = y \sin B$, so the required expression is the perimeter of $\triangle XYZ$, which means we only need to find the minimum perimeter of the pedal triangle of $\triangle ABC$. It is well-known that the perimeter of the pedal triangle is minimized when it is the orthic triangle, and since $HD \perp BC, HE \perp CA, HF \perp AB$, the orthocenter is the desired point.