1.Two semicircles of radius 6 units are inscribed in a semicircle of radius 12 units. A circle is inscribed so that it is tangent to all three semicircles. Find the circumference of the circle

2. In triangle ABC, AB=260, AC=400, and BC=520. Point D is chosen on BC so that the circle inscribed in triangle ABD and ADC are tangent to AD at the same point. What is the length of BD?