Since $OB = OP$, $\angle OBD = \angle OPD = 90^\circ$, and the common side $OD$, the triangles $\triangle OBD$ and $\triangle OPD$ are congruent. Thus, which leads to
$$\angle BOD = \angle POD$$
Similarly, $\triangle POE$ and $\triangle COE$ are congruent, andleading to
$$\angle POE = \angle COE$$
Therefore, $\angle DOP = \frac 12 \angle BOP$ and $\angle EOP = \frac 12 \angle COP$, which yields,yielding
$$\angle DOE = \frac 12 \angle BOC$$