菱形面积计算 by Jordan Varney
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①本范例演示如何通过构造菱形的对角线来计算其面积;②涉及核心数学概念包括菱形性质、对角线垂直平分、勾股定理、三角形面积公式;③作图要点:使用Segment, LineBisector, Point, Intersect, Polygon, Midpoint, Rotate, Angle等GeoGebra命令和对象进行菱形及其对角线的构造与测量;④适合初中及以上学生学习菱形面积计算方法,也可用于几何作图教学。
GeoGebra 命令及参数
Segment(A, B) → fLineBisector(f) → gPoint(g) → CPoint(g) → DIntersect(g, f) → EPolygon(A, E, C) → t1_1, c, a, ePolygon(C, E, B) → t2_1, b, c_1, e_1Polygon(A, D, E) → t3_1, e_2, a_1, dPolygon(D, E, B) → t4_1, b_1, d_1, e_3Midpoint(e) → FMidpoint(e_2) → GMidpoint(e_3) → HMidpoint(e_1) → IRotate(A, t1, F) → A'Rotate(E, t1, F) → E'Rotate(C, t1, F) → C'Polygon(A', E', C') → t5, c', a', e'Rotate(C, t2, I) → C'_1Rotate(E, t2, I) → E'_1Rotate(B, t2, I) → B'Polygon(C'_1, E'_1, B') → t6, b', c'_1, e'_1Rotate(D, t3, H) → D'Rotate(E, t3, H) → E'_2Rotate(B, t3, H) → B'_1Polygon(D', E'_2, B'_1) → t7, b'_1, d', e'_2Rotate(A, t4, G) → A'_1Rotate(D, t4, G) → D'_1Rotate(E, t4, G) → E'_3Polygon(A'_1, D'_1, E'_3) → t8, e'_3, a'_1, d'_1Angle(C, E, A) → αAngle(C, E'_1, B) → β