如图,将边长为m的正方形纸板沿虚线剪成两个小正方形和两个矩形,拿掉边长为n的小正方形纸板后,将剩下的三块拼成新的矩形. (1) 用含m或n的代数式表示拼成矩形的周长; (2) m=7,n=4,求拼成矩形的面积. 答案:解:矩形的长为:m﹣n,矩形的宽为:m+n,矩形的周长为:2[(m-n)+(m+n)]=4m
解:矩形的面积为S=(m+n)(m﹣n)=m2-n2,当m=7,n=4时,S=72-42=33 Do you think an English film tomorrow night? A. is there B. there is going to be C. there is going to have D. will there be