题目

如图，△OAC和△BAD都是等腰直角三角形，∠ACO=∠ADB=90°，反比例函数y=在第一象限的图象经过点B，则△OAC与△BAD的面积之差S△OAC﹣S△BAD为（ ）A. 36 B. 12 C. 6 D. 3 答案：【答案】D【解析】设△OAC和△BAD的直角边长分别为a、b，结合等腰直角三角形的性质及图象可得出点B的坐标，根据三角形的面积公式结合反比例函数系数k的几何意义以及点B的坐标即可得出结论． 解：设△OAC和△BAD的直角边长分别为a、b， 则点B的坐标为（a+b，a﹣b）．∵点B在反比例函数的第一象限图It is said that the early European playing-cards__for entertainment and education. A. were being designed      B. have designed C. have been designed      D. were designed