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人教版数学教材九年级上册第47页有这样一道例题:如图22.3-1,要设计一本书的封面,封面长27cm,宽21cm.正中央是一个与整个封面长宽比例相同的矩形,如果要使四周的彩色边衬所占面积是封面面积的四分之一,上、下边衬等宽,左、右边衬等宽,应如何设计四周边衬的宽度(精确到0.1cm)?
There is such an example: Figure 22.3-1, to design a book cover, cover length 27cm, width 21cm. The center is a ratio of the width and width of the entire cover the same rectangle , If you want to make the area around the color edge of the cover is a quarter of the cover area, the upper and lower lining lined width, left and right lining width, how to design the width of the surrounding lining (accurate to 0.1cm)?