No 10. What is the measure of angle BAC?

The image shows a circle with center O and a point A outside the circle. A line segment AB is tangent to the circle at point B. A point C is on the circle. The angle between the tangent line at B and the chord AB is marked with a question mark. There is also a chord from O to B, which is a radius, and a chord from O to A. There are tick marks on OB and a segment from O to the midpoint of OB. This information is insufficient to solve for angle BAC. To solve this problem, more information is needed, such as the measure of angle BOC or the length of OA. Since there is insufficient information, I cannot provide a numerical answer. The image contains geometrical figures which are not solvable with the given information and lack of context. Therefore, I can only describe what is visible in the image and state that it is unsolvable with the provided information.