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正方形是有多条对称轴的轴对称图形,又是中心对称图形.它是一种特殊的平行四边形,既具有矩形的一切性质,又具有菱形的一切性质.有关正方形题的证明与计算,一直为中考命题的重点内容之一. 例1 (1998年上海市闵行区)已知:正方形ABCD中,M是AB的中点,E是AB延长线上一点,MN⊥DM且交∠CBE的平分线于N(如图1).(1)求证:MD=MN.(2)若将上面条件中的“M是AB中点”改为“M是
The square is an axisymmetric figure with multiple axes of symmetry, and it is a center symmetrical figure. It is a special kind of parallelogram that has all the properties of a rectangle and all the properties of a diamond. The proof and calculation of the square question have been One of the highlights of the examination proposition. Example 1 (Minhang District, Shanghai, 1998) It is known that: In the square ABCD, M is the midpoint of AB, E is the point on the AB extension line, MN ⊥ DM and the CBE is divided equally. Lines in N (Figure 1). (1) Verification: MD = MN. (2) If the condition above is changed from “M is AB midpoint” to "M is