# Measure of a Bisecting Angle

Geometry Level 3

Circle $\Gamma$ with center $O$ is tangential to $PA$ at $A$. Line $PO$ extended intersects $\Gamma$ at $B$ (i.e. $PO < PB$). $C$ is a point on $AB$ such that $PC$ bisects $\angle APB$. What is the measure (in degrees) of $\angle PCA$?

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