Two circles intersect at points **C** and **D**. Point **A** lies on the circle at the left, point **B** lies on the circle at the right. Find the positions of **A** and **B** (on their given circle) such that segment **AB** is at its maximum possible length, and points **A**, **C**, and **B** are collinear.

* Circle 1 Circle 2*

Hint Connect points A, B, and D. What can you say about the angles of the triangle ABD as A and B chnage their positions?