8. As shown in the figure, the diameter $A B$ of $\odot O$ intersects the chord $C D$ at point $P, C P=\frac{7}{5}$, $P D=5, A P=1$, then $\angle D C B=$ $\qquad$
According to the intersecting chords theorem, we have $A P \cdot P B=C P \cdot P D \Rightarrow P B=7$. Connect $O D$. Then $O D=4, P D=5$, $P O=3 \Rightarrow O D \perp A B$, so $\angle D C B=\angle D A O=45^{\circ}$.