The centripetal acceleration and the position vector radius are always perpendicular to each other.
The centripetal acceleration is the acceleration experienced by an object moving in a circular path. It is directed towards the center of the circular path. The position vector radius, on the other hand, points from the center of the circle to the position of the object.
By definition, the centripetal acceleration is always perpendicular to the velocity vector of the object, which means it is also perpendicular to the position vector radius. This is because the velocity vector is tangential to the circular path and the position vector radius is radial.
So, to summarize, the centripetal acceleration and the position vector radius are always perpendicular to each other.