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求线段的最值,同学们往往感到困难,对于一类求线段的最大值和最小值得问题可以利用以下模型求解.一、建立模型已知:线段AB=6,线段AC=4,固定线段AB,将线段AC绕点A旋转,探求线段BC的最大值和最小值.分析为了求到线段BC的最大值和最小值,先构造一个含有线段BC的三角形,而且另外两条边是有数值的线段,如图1(1).线段AC绕点A旋转,当C落到BA延长线上
Find the maximum value of the line segment, students often feel difficult, for a class of seeking the maximum and minimum value of the line can be used to solve the following model problem: First, the model is known: line AB = 6, line AC = 4, fixed line AB , The line segment AC is rotated around point A to find the maximum value and the minimum value of the line segment BC.Analysis In order to find the maximum and minimum values of the line segment BC, a triangle containing the line segment BC is constructed first, and the other two edges have values Line segment, as shown in Figure 1 (1). Line AC around point A rotation, when C falls BA extension line