Problem 15.3b: If P is a point on the radical axis of two circles, C and D, then any circle with center P that intersects C at right angles also intersects D at right angles. Assignment 6
Problem 15.3c: If three circles intersect each of the other two circles in two points, then the three chords so defined intersect in a common point. See Figure 15.8. Assignment 6
Figure 15.8: Intersecting Chords