告诉12岁的孩子，如何解决这道6年级的数学题---**Question Number:** 20 **Question Stem:** 如图, 一个梯形被它的两条对角线分成了4个三角形, 已知三角形AOB和三角形AOD的面积分别是12平方厘米和6平方厘米, 那么这个梯形的面积是( ) 平方厘米. **Translated Question Stem:** As shown in the figure, a trapezoid is divided into 4 triangles by its two diagonals. Given that the areas of triangle AOB and triangle AOD are 12 square centimeters and 6 square centimeters respectively, then the area of this trapezoid is ( ) square centimeters. **Diagram Description:** * **Type:** Geometric figure, specifically a trapezoid with its diagonals drawn. * **Shape:** Trapezoid ABCD. The parallel sides are not explicitly stated in the diagram, but the standard representation of a trapezoid with diagonals intersecting at O suggests AD is parallel to BC or AB is parallel to DC. Based on the relative areas (AOB=12, AOD=6, BOC=24, COD=12 derived from calculation/handwriting), it is likely that AD is parallel to BC. * **Elements:** * Vertices: A, B, C, D. A is top-left, B is top-right, C is bottom-right, D is bottom-left. * Diagonals: AC and BD, intersecting at point O. * Triangles formed: AOB, BOC, COD, AOD. * **Labels and Annotations:** * Vertices are labeled A, B, C, D. * Intersection point is labeled O. * Area of triangle AOB is labeled "12". * Area of triangle AOD is labeled "6". * Handwritten label "24" is placed within triangle BOC. * Handwritten label "12" is placed within triangle COD. **Given Information:** Area(triangle AOB) = 12平方厘米 Area(triangle AOD) = 6平方厘米 **Question:** Find the area of the trapezoid ABCD. **Handwritten Text (Potential Solution/Answer):** Handwritten text after the blank in the question stem: "平方厘米. 54" suggests the answer is 54 square centimeters. Handwritten values in the diagram (likely intermediate results or parts of the solution process): Area(triangle BOC) = 24, Area(triangle COD) = 12.