Line CD is tangent to circle O. Line AB is a secant of circle O. Drag A, B, and C to adjust the lines. The spreadsheet to the right shows the value of the measures of the arcs and angles in the circle.[br][br]1. How is the measure of angle BAC related to the purple arc AB?[br][br]2. How is the measure of angle BAD related to the green arc AB?[br][br]3. Show the radii OA and OB. How would angle AOB relate to angle CAB?[br][br]4. Hide the radii again. What is the only way that angles BAC and BAD can be equal?