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现将有关一道2012年“旋转”中考题的思考整理出来,希望对同学们学习旋转、圆的相关内容有所帮助.例1(2012年义乌市中考题,有删减)在锐角ΔABC中,AB=4,BC=5,∠ACB=45°,将△ABC绕点B按逆时针方向旋转,得到ΔA_1BC_1.(1)如图1,当点C_1在线段CA的延长线上时,求么CC_1A_1的度数;(2)如图2,点E为线段AB的中点,点P是线段AC上的动点,在ΔABC绕点B按逆时针方向旋转过程中,点P的对应点是点P_1,求线段EP_1长度的最大值与最小值.
Now on a 2012 “rotation ” examination questions out of thinking, I hope the students learn about rotation, the contents of the circle to help .Example 1 (Yiwu City 2012 senior high school entrance examination questions, there are cut) at the acute angle ΔABC AB = 4, BC = 5, ∠ACB = 45 °, and rotate ABC around point B counterclockwise to obtain ΔA_1BC_1. (1) When point C_1 is on the extension of segment CA, (2) As shown in Figure 2, the point E is the midpoint of the line segment AB, the point P is the moving point on the line segment AC. During the rotation of the ΔABC around the point B in the counterclockwise direction, the corresponding point of the point P Is the point P_1, find the maximum and minimum length of the line segment EP_1.