Two Intersecting Circles

The two circles intersect at points C and D. Points A and B are placed each on one of the circles such that A, B, and C are collinear. ** Moving the red dot will change the positions of points A and B. 1. Do the dimensions of triangle ABD (side lengths and angle measures) change when points A and B change their positions? 2. Where do points A and B have to be placed for the length of AB to be maximum? 3. What is the measure of angle ACD when segment AB is at its maximum length?