题目列表(包括答案和解析)
3、如图,已知正方形和点O,画一个正方形,使它与已知正方形关于点O成中心对称。
2、画出三角形ABC绕点O逆时针旋转90°后的三角形。
1、在纸上画一个长为2㎝,宽为1㎝的长方形。然后画出将该长方形向北偏东45°方向平移2㎝后的图形。
22.(12分)如图,△ABC的两条中线AM、CN交于点G,在AM的延长线上取MD=GM,在CN的延长线上取NE=GN,连结BD、CD、BG、BE、AE. 请指出图中所有的平行四边形,并分别写出理由.
21.(12分)以给出的图形“〇、〇、△、△、=”(两个相同的圆、两个相同的三角形、两条平行线)为构件,各设计一个构思独特且有意义的轴对称图形和中心对称图形.举例:如图所示,左框中是符合要求的一个图形,你还能构思出其他的图形吗?请在右框中画出与之不同的图形.
20.(11分)如图,在10×5的正方形网格中,每个小正方形的边长均为单位1,将△ABC向右平移4个单位,得到△A′B′C′,再把△A′B′C′绕点A′逆时针旋转90°,得到△A″B″C″.请你画出△A′B′C′和△A″B″C″.
19.(11分)如图,在△ABC中,AD是中线.
(1)(3分)读语句画图:延长AD到点E,使DE=AD,连结BE、CE;
(2)(4分)填空:点A与点 关于点 成中心对称,线段AB与线段 关于点 成中心对称;
(3)(4分)写出所有关于点D成中心对称的三角形.
18.····························································································································································· 以不共线的三点为顶点作平行四边形可作出·············································································································································· ( ).
(A)1个 (B)2个 (C)3个 (D)4个
17.下列各组条件中,不能判定四边形ABCD为平行四边形的一组是·················· ( ).
(A)AB=CD,AD=BC (B)AB∥CD,AB=CD
(C)AB=CD,AD∥BC (D)AB∥CD,AD∥BC
16.····························································································································································· 把26个英文大写字母看成图案:A B C D E F G H I J K L M N O P Q R S T U V W X Y Z,则成中心对称图案的字母共有 ( ).
(A)4个 (B)5个 (C)6个 (D)7个
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