2012年12月8日SAT数学每日一练

　　下面是一道SAT数学练习题，答案在下一页，请自行完成后参看答案和解析。

　　Read the following SAT test question, then click on a button to select your answer.

　　A 25-foot ladder is placed against a vertical wall of a building, with the bottom of the ladder standing on concrete 7 feet from the base of the building. If the top of the ladder slips down 4 feet, then the bottom of the ladder will slide out

　　A.4 feet

　　B.5 feet

　　C.6 feet

　　D.7 feet

　　E.8 feet