Which point is interior to ∠ABC ?
Only point P is interior to ∠ABC. Point R is interior to ∠CBD but exterior to ∠ABC.
Point Q lies on the ray BC so it is not interior to ∠ABC. Point B lies on the ray BC so it is not interior to ∠ABC.
ABC is a triangle. Locate a point in the interior of ΔABC which is equidistant from all the vertices of ΔABC.