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新课标中“旋转变换”,是保持两点间距离不变的变换。通过旋转变换后,往往能感受到图形变换的乐趣和价值。下面列举2005中考旋转变换试题几例, 供大家赏析。例1 (2005年南京市)在平面内,如果一个图形绕一个定点旋转一定的角度后能与自身重合,那么就称这个图形是旋转对称图形,转动的这个角称为这个图形的一个旋转角。例如:正方形绕着它的对角线的交点旋转90°后能与自身重合(如图),所以正方形是旋转对称图形,它有一个旋转角为90°。 (1)判断下列命题的真假(在相应的括号内填上“真”或“假”)。①等腰梯形是旋转对称图形,它有一个旋转角为180°。( ) ②矩形是旋转对称图形,它有一个旋转角为
The “rotational transformation” in the new curriculum standard is a change that keeps the distance between the two points constant. After the transformation by rotation, the joy and value of graphic transformation can often be felt. Listed below are several examples of the 2005 test rotation transformation test questions for everyone to appreciate. Example 1 (Nanjing, 2005) In the plane, if a figure is able to coincide with itself after rotating a certain point around a fixed point, the figure is said to be a rotationally symmetric figure. The angle of rotation is called a rotation angle of the figure. . For example, a square can be superimposed on itself (as shown) by rotating it 90° around its diagonal intersection, so the square is rotationally symmetric and has a rotation angle of 90°. (1) Determine the trueness and falseness of the following propositions (fill in “true” or “false” in the corresponding brackets). An isosceles trapezoid is a rotationally symmetric figure that has a rotation angle of 180°. () 2 The rectangle is a rotationally symmetric graph that has a rotation angle of