题干

正方形网格中,每个小正方形的顶点称为格点,以格点为顶点的三角形叫格点三角形.在图中正方形网格(每个小正方形边长为1)中有一格点△ABC和一线段DE

(1)以DE为一边做格点△DEF与△ABC相似;

(2)直接写出△DEF的面积.

上一题 下一题 0.0难度 选择题 更新时间:2018-10-26 10:18:34

答案(点此获取答案解析)

解:(1)如图所示,△DEF与△ABC相似;


(2)△DEF的面积=

同类题3

阅读理解

    Getting rid of dirt(灰尘), in the opinion of most people, is a good thing. However, there is nothing fixed about attitudes to dirt.

    In the early 16th century, people thought that dirt on the skin was a way to block out disease, as medical opinion had it that washing off dirt with hot water could open up the skin and let illnesses in. A particular danger was thought to lie in public baths. By 1538, the French king bad closed the bath houses in his kingdom. So did the king of England in 1546. Thus it began a long time when the rich and the poor in Europe lived with dirt in a friendly way. Henry IV, King of France, was famously dirty. Upon learning that a nobleman had taken bath, the king ordered that, to avoid the attack of disease, the nobleman should not go out.

    Though the belief in the merit of dirt was long-lived, dirt has no longer been regarded as a nice neighbor ever since the 18th century. Scientically speaking, cleaning away dirt is good to health. Clean water supply and hand washing are practical means of preventing disease. Yet, it seems that standards of cleanliness have moved beyond science since World War ll. Advertisements repeatedly sell the idea: clothes need to be whiter than white, cloths ever softer, surfaces to shine. Has the hate for dirt, however, gone too far?

    Attitudes to dirt still differ hugely nowadays. Many first-time parents nervously try to warm(警告)their children of touching dirt, which might be responsible for the spread of disease. On the contrary, Mary Ruebush, an American immunologist(免疫学家), encourages children to play in the dirt to build up a strong immune system. And the latter position is gaining some ground.