a problem regarding centre of similitude In the book Roger A. Johnson, _Advanced Euclidean Geometry_ on page no. 19 there is a theorem > from a point of intersection of two circles the lines to the centre of similitude bisect the angle between the radii of the circles. I am not getting what is the angle between the radii of the two circles. Please draw the figure for this theorem I shall be very thankfull.

Below is the illustration of the theorem (actually a corollary in the referenced book). Here $H$ is the internal center of similitude, $H_1$ is the external one, the theorem states that $IH$ bisects $\angle AIC$:![enter image description here](