题干

在平面直角坐标系中,△ABC的顶点坐标是A(﹣7,1),B(1,1),C(1,7).线段DE的端点坐标是D(7,﹣1),E(﹣1,﹣7).

(1)试说明如何平移线段AC,使其与线段ED重合;

(2)将△ABC绕坐标原点O逆时针旋转,使AC的对应边为DE,请直接写出点B的对应点F的坐标;

(3)画出(2)中的△DEF,并和△ABC同时绕坐标原点O逆时针旋转90°,画出旋转后的图形.

 

上一题 下一题 0.0难度 选择题 更新时间:2019-11-22 09:01:26

答案(点此获取答案解析)

解:(1)将线段AC先向右平移6个单位,再向下平移8个单位.(其它平移方式也可以);

(2)根据A,C对应点的坐标即可得出F(﹣l,﹣1);

(3)画出如图所示的正确图形.

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阅读理解

    A recent study, while showing a generally positive attitude toward science, also suggests a widespread worry that it may be "running out of control". This idea is dangerous.

    Science can be a force for evil as well as for good. Its applications can be channeled either way, depending on our decisions. The decisions we make, personally or collectively, will determine the outcomes of science. But here is a real danger. Science is advancing so fast and is so strongly influenced by businesses that we are likely to believe whatever decisions we come to will make little difference. And, rather than fighting for the best possible policies, we may step back and do nothing.

    Some people go even further. They say that despite the moral and legal objections, whatever is scientifically possible will be done-somewhere, sometime. They believe that science will get out of control in the end. This belief is dangerous too, because it fuels a sense of hopelessness and discourages then from making efforts to build a safer world.

    In our interconnected world, the lack of agreement in and out of the world of science can lead to the failure to control the use of science. Without a common understanding, the challenges of "controlling" science in this century will be really tough. Take human cloning for example. Despite the general agreement among scientists on its possible huge impact on traditional moral values, some countries still go ahead with the research and development of its related techniques. The outcomes are hard to predict.

    Therefore, discussions on how science is applied should be extended far beyond scientific societies. Only through the untied efforts of people with hope, can we be fully safe against the misuse of science and can science best serve mankind in the future.