回答9-6，并说出具体解题方法---Based on the image provided, here is the extracted content: **Introductory Text:** 采用两种极限情形来检查你所得到的的公式的正确性。已知球缺底部圆周上任一点与 dA1 之间的连线同 dA1 法线间的夹角为 β。 **Question 9-5:** 在附图中, l = 0.2 m, r₁ = 0.1 m, r₂ = 0.13 m, 试计算 Xd1,2。 **Diagram for Question 9-5 (习题 9-5 附图):** * **Type:** Geometric figure illustrating a physical setup for calculating a view factor. * **Main Elements:** * An infinitesimal area element labeled dA₁ at the top, oriented horizontally. * A vertical line of length labeled 'l' connecting the center of dA₁ to the center of a ring-shaped area below. * A ring-shaped area labeled A₂ below, oriented horizontally. It is an annulus (area between two concentric circles). * The inner radius of the annulus is labeled r₁. * The outer radius of the annulus is labeled r₂. * The area A₂ is shaded with diagonal lines. **Question 9-6:** 试用简捷方法确定附图中的角系数 X₁, ₂°. **Diagrams for Questions 9-6, 9-7, 9-8 (习题 9-6 附图):** * **Type:** Geometric figures illustrating different shapes for view factor calculation. * **Figure (a):** * **Type:** 2D geometric figure (cross-section of an infinite length geometry). * **Elements:** A sector of a circle defined by two radii at a 90° angle and a curved arc. * **Labeled Surfaces:** The curved arc is labeled '1'. One straight radial line is labeled '2'. The angle between the straight lines is labeled '90°'. * **Annotation:** "(a) 在垂直于纸面方向无限长" (Infinite in the direction perpendicular to the paper plane). * **Figure (b):** * **Type:** 2D geometric figure (cross-section of a hemisphere and its base). * **Elements:** A semicircle (representing a hemisphere in 2D) and a horizontal line (representing the base). * **Labeled Surfaces:** The curved surface (inner surface of the hemisphere) is labeled '1'. The base (circular area) is labeled '2'. A dashed line represents the diameter of the base. * **Annotation:** "(b) 半球内表面与底面" (Hemisphere inner surface and base). * **Figure (c):** * **Type:** 2D geometric figure (cross-section of a hemisphere and part of its base). * **Elements:** A semicircle (representing a hemisphere in 2D) and a horizontal line (representing the base), with a shaded region on the base. * **Labeled Surfaces:** The curved surface (inner surface of the hemisphere) is labeled '1'. The shaded region on the base is labeled '2'. The shaded region appears to be a quarter of the circular base, indicated by hatching. * **Annotation:** "(c) 半球内表面与 1/4 底面" (Hemisphere inner surface and 1/4 base). * **Figure (d):** * **Type:** 2D geometric figure (cross-section of a sphere and a plane). * **Elements:** A circle (representing a sphere in 2D) touching a horizontal line (representing an infinite plane). * **Labeled Surfaces:** The surface of the sphere is labeled '1'. The infinite plane is labeled '2'. Hatching indicates the plane. * **Annotation:** "(d) 球与无限大平面" (Sphere and infinite plane). **Question 9-7:** 试确定附图 a、b 中几何结构的角系数 X₁, ₂°. **Question 9-8:** 试确定附图 c、d 中几何结构的角系数 X₁, ₂°.