帮我讲解一下这些题---Here is the extracted content from the image: **Question 14:** **Question Stem:** 14. 如图, $AB$ 是 $\odot O$ 的直径, 点 $C, D$ 在 $\odot O$ 上, $OD \perp AC$, 若 $\angle B = 50^{\circ}$, 则 $\angle D = \_^{\circ}$. **Diagram Description (第 14 题图):** * Type: Circle geometry diagram. * Main Elements: * A circle with center O. * Line segment AB is the diameter of the circle, passing through O. * Points C and D are on the circle. * Line segments AC, BC, BD, AD are chords or parts of triangles within the circle. * Line segment OD is a radius. * OD is perpendicular to AC. A right angle symbol is shown at the intersection of OD and AC. Let the intersection point be E. * Angle ABC ($\angle B$) is given as $50^{\circ}$. * Angle ADB ($\angle D$) is the value to be determined. **Question 15:** **Question Stem:** 15. 如图, 在矩形 $ABCD$ 中, $CE \perp BD$, 垂足为点 $E$. 若 $AB=5, CE=3$, 则 $\triangle BCE$ 的面积为 \_ . **Diagram Description (第 15 题图):** * Type: Rectangle and line segments diagram. * Main Elements: * A rectangle ABCD. * Diagonal BD is drawn. * Line segment CE is drawn from vertex C, perpendicular to BD at point E. * A right angle symbol is shown at point E, where CE intersects BD. * Points A, B, C, D, E are labeled. * Given lengths: AB = 5, CE = 3. * The area of triangle BCE ($\triangle BCE$) is to be determined.