Perpendicular circles

Question

Let P and Q be two different points on a circle C. We assume that the points do not lay on the same diameter. Draw the tangents to the circle in P and Q and let R be their point of intersection. Let C' be the circle with center in R that goes through P and Q. Prove that C and C' are perpendicular. Prove also that C' is the only circle that passes through P and Q and is perpendicular to C.

Answer 1

Perpendicular is at a rt angle. C and C' can't be labeled that because there's not a 3rd pt.

As for pt "r" C' is the only one.

Another "r" can be placed on the other side of the circle using the same 2 points though.