问题详情:
“囧”像一个人脸郁闷的神情.如图,边长为a的正方形纸片,剪去两个一样的小直角三角形(*影部分)和一个长方形(*影部分)得到一个“囧”字图案,设剪去的两个小直角三角形的两直角边长分别为x、y,剪去的小长方形长和宽也分别为x,y.
(1)用含a、x、y的式子表示“囧”的面积;
(2)当a=12,x=7,y=4时,求该图形面积的值.
【回答】
(1)a2-xy×2-xy=a2-2xy;··························································(3分)
(2)当a=12,x=7,y=4时,
原式=122-2×7×4=88 ···········································································(6分)
知识点:整式的加减
题型:解答题