帮我讲解一下上面的题---**Question 9:** **Question Stem:** 如图，四边形 ABCD 内接于 O，∠ABC = 60°，∠BAC = ∠CAD = 45°，AB + AD = 2，则 O 的半径是 ( ) **Translation of Question Stem:** As shown in the figure, quadrilateral ABCD is inscribed in circle O, ∠ABC = 60°, ∠BAC = 45°, ∠CAD = 45°, AB + AD = 2, then the radius of O is ( ) **Given Information:** * Quadrilateral ABCD is inscribed in circle O. * ∠ABC = 60° * ∠BAC = 45° * ∠CAD = 45° * AB + AD = 2 **Question:** Find the radius of circle O. **Options:** (No options are provided in the image) **Chart/Diagram Description:** * **Type:** Geometric figure - A circle with an inscribed quadrilateral. * **Main Elements:** * A circle is shown. * The center of the circle is labeled as O. * Four points A, B, C, and D are on the circumference of the circle, forming a cyclic quadrilateral ABCD. * Line segments AB, BC, CD, and DA form the sides of the quadrilateral. * Line segment AC is a diagonal of the quadrilateral. * Point O is located inside the quadrilateral, approximately in the center. * The vertices appear in counter-clockwise order starting from A at the bottom left, B at the bottom right, C at the top, and D at the top left.