The Winter Olympics is also called the White Olympics．At this time，many colorful stamps are published to mark the great Games．The first stamps marking the opening came out on January 25th，1932 in the United States for the 3rd White Olympics. From then on，publishing stamps during the White Olympics became a rule.
    During the 4th Winter Olympic Games a group of stamps were published in Germany in November l936. The five Olympics rings were drawn on the front of the sportswear．It was the first time that the rings appeared on the stamps of the White Olympics．
    In the 1950s，the stamps of this kind became more colorful．When the White Olympics came，the host countries(主办国) as well as the non-host countries published stamps to mark those Games．China also published four stamps in February 1980 when the Chinese sportsmen began to take part in the White Olympics．
    Japan is the only Asian country that has ever held the White Olympics．Altogether 14,500 million stamps were sold to raise money for this sports meeting．
    Different kinds of sports were drawn on these small stamps．People can enjoy the beauty of the wonderful movements of some sportsmen.

①先裁下了一张长BC=20cm，宽AB=16cm的矩形纸片ABCD，

②将纸片沿着直线AE折叠，点D恰好落在BC边上的F处，

请你根据①②步骤解答下列问题：计算EC，FC的长．

将一元二次方程x²+2 $\sqrt{2}$ x+1=0左边配方成完全平方式之后，右边的常数应该是（   ）